Downpipe - No cat causes failure according to "Velocity Factor"...
 

So I was research Downpipes, and I found this:

2007-2011 MazdaSpeed 3 Performance Upgrade Guide - Stage 2 - VFR auto blog

Is there ANY truth to this, or do the just want to sell catted Cobbs?

I am planning on buying the Ultimate Racing Cattless Downpipe v3 with a high flow cat test pipe. This combo comes to $635, while the Cobb catted Downpipe is $695, and that's without the test pipe. Is the cobb really that much better?

There's also the ATP long catted DP for $495, but I thought the UR setup would be the best in between option.

But what's this about needed a cat in the downpipe or the turbo can fail? I don't get it...

Just go for the cheapest dp, imo. Your turbo won't fail unless you do stupid things.

Tons of people running catless with no problems.

Thank you for the reassurance! I know so many people run cattless, I couldn't see how this was true. Sounded like a Cobb sales pitch from a vendor.

Anyways, ATP vs Ultimate Racing: Any major difference? The ATP is noticeably cheaper, $489 vs $635.

I know I could go eBay DP, but generic parts on my engine scares the bajeezus out of me!

It's just a damn metal pipe. As long as it fits, why the hell would you need to spend 4-6 times the price of the Ebay one?

LOL, so it fits & doesn't leak/break. Plus I want a good quality Cat. Are you implying the a cheapo ebay knock off is really no different?

I've been running an M2 Downpipe with a Magnaflow high-flow catalyst for several years now. The only problem I've ever had was getting the OEM pipe and catalysts out. I spent about $120 on the whole shebang, as I bought the downpipe used.

That all being said, thanks to the climate-science denialism going on, I'm actually going to swap the OEM shit back in, and work on a low emissions-based tune instead of only performance/fuel economy-based tunes.

You could spend $350 on a CPE catted downpipe...

LOL, I love it!

Environmental friendliness is my primary reason for wanting to run a high quality high flow cat. While it may not be quite as low emissions as stock, I'm sure it's a million times better than cat-less. I have a 5 month old Son and an environmentally conscious wife. I promised her I wouldn't cat delete. Plus, I don't want my son breathing non catted exhausts.

That being said, maybe I could find an eBay short downpipe and then get a high flow Cat test pipe. Reliability is big for me, too, that's still my big concern with the ebay knock offs. Though some seem pretty popular.
@Bingo;

I've been eyeing the CP-E catted downpipe you have for a while. My concern, again, is reliability, especially on a used part. I've read some of the older CP-E's coming apart at the welds, and poor fits. Not that yours would! :)

If environmental friendliness is important to you, you should remember that no matter which catted downpipe you install, you're doing at least three things that are environmentally detrimental:

1. You're replacing two catalysts with one, and in all likelihood removing the light-off catalyst that reduces emissions dramatically at start-up.

2. The one catalyst you're installing is a "high-flow" catalyst that is substantially less environmentally efficient than either of the two you're removing. So called, "high flow catalysts" have fewer cells, at lower cellular density, and with lower levels of rare metal catalyst disposed on the substrate. They are far less effective at removing environmentally harmful material from the exhaust stream than OEM catalytic converters.

3. You're going to have to tune the car differently to run the freer-flowing downpipe. The result of this is that you're probably going to be running a somewhat different stoichiometric mixture than you would if you were running the stock exhaust system. The result of this is that you'll have higher percentages of NOx and Sulfur constituents in your exhaust than if you ran a stock tune, or a stock set of catalysts.

Anyway, it's food for thought.

"Environmental friendliness is my primary reason..."

Why are you driving a decade-old, turbocharged, petrol-burning Mazda?



Sent from my LG-E980 using Tapatalk

All of your points are well taken, but there are degrees of environmentally friendlyness...

It's not just one or the other. It's not Prius or 68' Big Block GTO. I can tune my car and have fun with it without taking off all emissions systems. Keeping at least one high flow cat will still keep the exhausts far cleaner than catless. Will it be as clean as stock? I sincerely doubt it, unless something is severely wrong with my OEM Cats.

I never thought a single high flow cat with a tune will keep the exhaust just like stock. But, if I'm going to do these upgrade, I do NOT want to go full Catless. From my understanding, having one high flow Cat is still many times cleaner than catless. And by cleaner, I don't mean less CO2, I mean less NO, sulfur, etc.

That being said, another option is to skip the DP, and just go intake, TMIC, & tune. It will cost less, but will it be as fun? Probably not! :haha:

Back to the actual point...

The eBay Downpipes are all Catless and full downpipes. So if I buy a cat sperately and have to pay to have it added in, I'm going to be much closer to a $500-700 premade one. Exhausts shops around here are stupid pricey. I called a locally recommended shop, and the guestimated $200-400 to add a cat to the downpipe.

So what it comes down to is that if I want a Cat, I need to buy one premade that way, such as the ATP, UR, CS, or CP-E. Please correct me if my logic is off somewhere! :)

My bicycle doesn't have any cats.

My bicycle does have a cat. https://uploads.tapatalk-cdn.com/201...628ebfd56c.jpg

crapatalk it sucks for free

https://s-media-cache-ak0.pinimg.com...c69192ddb8.jpg
@neganox; @WetzMS3;

Ok so all i go out of this thread is go buy a prius im a pussy.

FYPN

Your downpipe with the 100-200 cell cat isn't doing anything for environment. You'll still smell fumes, not as much as completely catless, but you'll smell them. You live in Florida. Catless all the things man.

Fyi- launch control with two cats still pukes black smoke out the exhaust.
https://sites.google.com/site/catpuk...tvomitGOLD.jpg

@KiwiFlavor; knows about dem cats.

Sent from my Nexus 6P using Tapatalk

I love dem shaved cats.

Please explain how getting an intake, upgraded tmic, and tune would be less fun than getting a downpipe?

If you care about exhaust "cleanliness", you got the wrong car.

Idk bruh?
https://thumbs.gfycat.com/ShockingRa...restricted.gif

Because alternative reasons?!

Sent from my Nexus 6P using Tapatalk

LOL, I love the direction this thread has gone.

What I'm hearing is that if you bought this car, you must hate the planet anyways, so why have cats at all... :haha:

I still stand by that a single high flow cat is better than no cats. And it is! How much is debatable, but w/e. My wife finds it acceptable as long as I have one and that's what matters.

Think of how much less polluting we would be as a community if all you catless had at least a single high flow cat? There, I'm putting it back on you.

Why does a downpipe make the car more fun? I've heard 1 million times that the 2nd cat is the most restrictive part, bla bla bla. On top of that, sound effects, smoother power curve, more torque everwhere, etc. I know it's a rhetorical question anyways. Almost everyone here is tuning their car to be faster or more fun, not environmentally friendly.

At this point, I'm debating on whether to take a chance on Bingo's used CP-E catted DP he's been trying to sell all year! :smokin:

I had a cat on my cs downpipe. I'm not sure removing it would have added that much power. The less restrictions you have on the exhaust the easier it is to spin up the turbo. On my SRT4 Neon I had a side exit exhaust with a single cat and that was perfect for spool. It's partly about what your goals are for the car. If you want the absolute most power you can make then maybe no cats a better option. You'll run out of fueling and rod strength on a stock block before youd need to be catless for max powarrr.

crapatalk it sucks for free

We don't hate the environment, just Prius drivers.https://uploads.tapatalk-cdn.com/201...c163016723.jpg

crapatalk it sucks for free

@Carskick; No one is going to spoonfeed you technical knowledge or write a novel in a forum about the differences between restricting/unrestricting the compressor and/or turbine side of the turbo. If you are really interested- do more reading on the profusion K04 bolt-on builds and pick up some technical books and white papers, such as "maximum boost" by corky bell (VIP vault, I think) and the EFR training manual.

I can tell you that nearly completely unrestricting the compressor side of my modified K04 with a bar&plate 3.25" TMIC, 4" intake and low ethanol mix (~e30) has hit a flow wall with the two stock cats. Below are two logs from tonight, pushing 41-42lb/min and only seeing low 300's at the wheels. I can speak from experience, that the unmodified K04 with only a 4" intake (stock 2 cats and stock intercooler) spools stupidly fast- coming from someone appreciates response in AX racing.

If you don't have high HP power goals, then throw a big intake on the K04 and call it done- the downpipe question is irrelevant.

http://i1318.photobucket.com/albums/...ps1k4nm0xn.png

http://farm5.static.flickr.com/4038/...3a636a334a.jpg

https://buffetoblog.files.wordpress....fler.jpg?w=652

I know I've said this many times, but I feel having the information everywhere cannot hurt. lol

The only thing that I would like to be noted as a difference between an ebay DP, and a more expensive DP like the ATP, is the rear o2 bung being extended. AFAIK, the 1st gen speed3s, like what you have, will not throw a check engine light because of this. I could be misinformed, as I do not own one. However, some pu owners have had issues with it (myself included). I get multiple check engine lights for rear o2 codes, because of that extended rear o2 bung.

Maybe someone can shed more light on first gen cars, but IIRC, they do not have the same issue. If you are reading this, and have a pu, then I would recommend having someone weld in a standard height rear o2 bung before installing the downpipe.

With that said; none of this has any impact on tuning. Personally, I have never come across any sort of information, or even claims for that matter, to suggest that bung location has caused a tuning issue. The primary, aka the one that matters, all seem to be in basically the same spot on all aftermarket downpipes.

Nor do I want to be spoon-fed. I've been spending a lot of time trying to find the right information to make my decisions. But getting different opinions doesn't hurt.

So to your point... The intake is the biggest thing that improves spool time for the K04. That will be done, in fact, I already have my 3.0" JBR WP ready to install once I get my AP and any other parts.

At this time, I'm looking at mods that add power throughout the band while maintaining reliability. A little more aggressive noise is good, but don't want to be excessive...

According to CS' dynos, the downpipe added torque throughout the entire power band, and the power seems smoother. Plus a little bit meaner exhaust without too much is appealing. That's another reason to keep a Cat for me, as it quiets things down a bit.

And compared to the CS setup, I'm looking at a larger intake and a larger TMIC. So wouldn't I really be hitting the limits of stock DP? This is why I was planning on this upgrade.

Very good info. I'd heard something about this before where gen pu's were more sensitive to the placement of the rear o2 sensor. Glad it doesn't affect tuning. But my biggest problem with ebay DPs is the lack of a cat, which I'm still insisting on having one. :horse:

You could just do a test pipe. I hear e85 is made from plants!!!!

That's a very budget friendly solution, and was my original plan before I decided to go full downipipe. SUPPOSEDLY... The downpipe smooths out the torque curve. Does it really matter? Meh...

E85 is made from taco shells or something, right?

If i went back and had to do it all over again i would still go test pipe and e85. Test pipe install was a joke compared to a dp. Fuck that down pipe...... e85 will make the diffrence between TP and DP small. Besides im sure you can snag a test pipe on the cheap in the FS section.
E85 is made from corn. It is green energy kinda and it supports merica jobs!

LOL, yeah, I know all about E85 in terms of the product, just adding to the sarcasm!

I've toyed with the idea of an E30-50 tune, but there are a couple of things holding me back:

1. Only 4 gas stations in my town have E85, and many of the places I travel to don't have it available
2. I'm often in a hurry at a gas station, so having to retune when E85 is not available isn't a good option for me
3. The only stations that sell E85 are not stations I want to buy my 93 from (RaceTrack)

My plan ATM is to just get a 93 tune. I can always have an E30-E50 tune done down the road once it's readily available in my area. I'd love it if E30 premix became widely available! :)

I won't be installing the DP myself, but paying my mechanic to do it. Probably 2-4 hour charge I'm guessing. The test pipe would probably take what, 30 minutes? Maybe I should save the money and efford of the DP and go Test pipe. I could do the UR testpipe, so if I wanted to add a UR DP in the future, it would match up.

That being said, I could get a high flow cat as my test pipe...

The sooner you forget the concept of the right solution or the right information/truth, the happier you're going to be with your car. Modding (and learning about and living with a modded car) is analogous to the course of a disease or a feedback loop. One mod begets another mod, usually in increasing magnitude.


Or, the large intake is the only hardware mod needed (aside from e and pump internals) if you are truly committed to a build with stock cats.


Your statements in relation to CS's published dyno's belies your lack of experience with tuning and boost control systems. Invest more in reading and practice tuning a car and re-evaluate those graphs.

Please re-read my post about the hp limit with stock cats. Then spend some time reading about tuning the boost control system.

Do yourself a favor. learn to tune on e- it will make your life much, much easier.
Then, if you absolutely can't live with finding e pumps, then switch to 93

I am perfectly happy with my car. Adding a bit of extra power, faster spool, and a better sound for my needs is what I am after. I am trying to do all of these mods together as a "phase", as I am planning to have an e-tune done and want to minimize the re-tuning that would be required if I did one mod at a time. So I'm researching, asking questions, getting different opinions, learning, etc. I understand there is not one truth or one correct path. Most mods and options have pros and cons, so there can never be one "right" answer.

I haven't committed to using only stock cats. I was planning on using a single high flow when I began this post. If the stock cats are the most limiting factor post intake replacement, the logical solution would be to upgrade or remove them. This begets either a long DP with a high flow cat, or at the least, a test pipe in place of cat 2.


I am curious what you are referring to here. Again, I do not wish to be spoon fed, but I have read many a dyno graph. While I don't consider myself anywhere near expert level, I do understand the relationship between power, torque, RPMs, and what the graph means. When I look at the three graphs, I see that the downpiped version has more Torque early on, maintains a more even arc, not dropping off as rapidly after peaking as the stock version does. The intake/racepipe graph has more dips and fluctuation, though it actually has higher torque peaks than the downpiped version. Assuming these graphs were 100% accurate (which I am aware dynos are not), I'd prefer a smoother, flatter torque curve. Am I missing something?

I re-read what you said. You say that I will hit a "Flow Wall" with the stock cats, but then you say just do the intake, tune and run ethanol. If the stock cats cause a hindrance to flow, why would I not want to replace them? I'm missing something here...

Please see my post just before yours. I would love to run an ethanol tune. But it's not practical for me right now. I have to make unplanned trips up to 120 miles away for work and am often on a time crunch. Many of the places I go do not have Ethanol stations. And I do not always have time to flash a tune before filling up. I wish this weren't the case, but it is. Plus, our cars have small gas tanks! :lame:

Once I have completed and am comfortable with my mods and a 93 tune, then I may begin messing around with Ethanol. But I'm not ready to take that plunge, as it adds another level of complexity.

I really appreciate the feedback and advice. Believe it or not, I have done TONS of reading on turbo theory, and there is so much I still don't know, which is why I'm still researching and asking questions! :arms:

Sorry to quote the whole thing as I'm on my phone. I've been using E85 and 93 from Racetrack for a few months now. Got tired of taking a gas can of E to Mobile and said, "Why not?". Not experiencing any knock. I would stick to top tier stations if I go back to 93, but the E negates the slightly sub par fuel.


Sent while probably pooping

Yes, you're missing something here.

And I routinely travel to different states where ethanol is few and far between. Plan, and it's not a big deal. If you get stuck in a situation where you absolutely can't find it, you can still run 93, but will have to stay away from boost and watch for knock.

If anything, ethanol will greatly simplify tuning and reduce the impact of the eventual hardware changes.

Having a cat will help you with drone, but if that's something you insist on having, perhaps you should take 5doors advice and just do a test pipe.

A full catless downpipe will give you an incredibly faster full boost spool. Like, if you think you had insta-spool before, wait until there are zero flow restrictions. lol It's quite nice.

As for the E85, IMO if it's remotely feasible, I'd do it. Peace of mind from knock, more power, and you can always flash back to 93 if you need to. It is an inconvenience for sure, I'm not going to lie about that, but that extra 30-40 whp is a pretty big difference. You figure out all the little details with time.

You might just find that it's completely worth the extra time. It ain't like we do it just because we like to stand at the gas pumps longer. lol

Thats a good point. Ethanol can help offset the worse 93 octane gas. lol. I wish Shell, Chevron and Mobile would just carry E85, or better yet, E30! :wtf1:

If only I knew what it was...

I understand your point, it's do-able. Just more work/planning on a regular basis.

Although I will have to get two tunes done: A 93 tune, and an Ethanol blend tune. But as you say, ethanol is proven to increase power and reduce knock. Power increase via ignition timing advance, if I understand correctly.

Very helpful info, thank you! The insta-spool & increased torque throughout were my main motivations for the DP. I believe even a high flow catted DP will still get me these type of results. I've read multiple times the main reason for this is that the part the hooks to the turbo (can't remember the name of it) is larger, curvier, and less restrictive. On top of that, the pipe is larger and either has no cats, or hi-flow.

So if a test pipe costs $60 on ebay, and a quality catted downpipe costs $500-700, the question becomes is it worth the money & install hassle? I think the answer right now is to just get the TP, and start with that. I can always add DP later. I really do appreciate all the input.

I've been told by 50+ people that I need to E tune... I guess I should listen. The E-Tuners charge $50 to add an Ethanol blend. I've been covninced, I might as well. So if I want max power on a tank, I can run it. See? You all won! :neener:

IMHO, there's no reason at all to buy a high-flow catted downpipe. They're expensive as hell, don't really do shit for emissions, and often end up falling apart internally eventually. Either go catless, or just run a test pipe. As far as testing for emissions goes, you can pass the scans all day by turning off the code.

To not tune the car at all, is a complete disservice to yourself. These cars are much more fun when tuned, and can drive completely different than a stock vehicle, depending on how your tuner puts together your tune. Throttle input characteristics, spool characteristics,etc. can all be manipulated. If you drove them blind, 2 cars could feel so different you may not even realize they're the same car. Hell, you can make the KO4 feel exactly like a BT through tuning.

After owning one of these cars modified, I would never go back. I've driven a stock car since I did everything to mine, and it sucks. lol

After all the feedback, I am in full agreement. I decided to go ebay Speed Daddy Testpipe and call it a day.


I think you misunderstood what I was trying to say... I see where I added to the confusion. I was talking about an Ethanol Tune, and I said E Tune. Since I am getting a 3" Intake, I HAVE to do a tune, whether I want to or not. But to me, e-tuning was never a question, it's a requirement. Ethanol Tuning was the question, though I've decided to go ahead and E-30 tune after we get the 93 tune figured out. In fact, I'm currently running a 91 Stage 1 Cobb OTS since I got my AP last week. I was running 93, but the car is running a little lean, probably from an intake leak, so I am running 91 for safety ATM.

All remaining parts have been ordered for my build, and I've started the Freektune process. I'm shooting for a completed install June 2nd. Then I will just be revising tunes, and eventually, E-30 tune. I'm very excited!

You must tune the car if you run a catless dp and rp. Otherwise you will overboost by at least 2 psi and hit boost cut with nssty 21-22 psi boost spikes under certain conditions. Also, you must upgrade the high pressure fuel pump internals as the pump cannot keep up with the increased fuel demands and will drop pressure to unsafe levels. Looks like you already have the pump internals. You will want to verify that.

But, with catless dp/rp, internals, a CAI or SRI intake and even a conservative tune it pretty much maxes out the K04 on pump gas at just over 300 whp 300 torque. With an E tune as you plan you can probably get it up to 320-330 whp.

I've been running the catless TurboXS dp/rp for over eight years with mods below. Catless is also loud and droning even with stock CBE. I added a straight through reso in the rp section. That killed the drone with no detectable power loss.

The setup outflows the K04 on pump gas.

FWIW, @Carskick;, Speed Daddy does sell a shorty DP for our car; I just ebay'd one last week for about $85 shipped. If you haven't ordered the test pipe yet, that could be an option id you still want to try to pull off a catless DP/catted TP setup for fewer dollars.

I saw that, but I decided to just go TP and be done. Primary reason was cost of install and less risk of something going wrong. I may eventually change it, but that's the current plan.