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Discussion Starter #1
I'm going to be in the market for a downpipe to move my 2010 WRX to stage 2. I currently have the SPT CBE and like the sound I get from it. My question is, what are the main differences in performance/feel between a catted and catless DP. I'm new to tuning and recently flashed a TP map using tactrix so I'd be getting a TP stage 2 map and flashing right after I figure out what kind of DP I want and get it installed. I'm not looking to spend a ton of money on a DP (if possible) so I'd also like suggestions on some good deals. I live in Iowa and we currently have no emission checks so I wouldn't really have to worry about that (which may be a reason many need a catted DP??). I'm pretty new to this stuff so ignore my ignorance if possible. Also, going to a catless DP, would that throw codes or cause any issues? Thanks!
 

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The Fruit
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personally I'd go catted and there are a couple of reasons why;

-It helps mitigate boost creep problems that the 09 n later cars have.

-You may not always live somewhere that doesn't do emissions..and where you live could always start doing emissions testing. Technically its FEDERAL regulation so could come into effect at any time. Or you could swing better job somewhere else.. etc. Never hurts to be legal.

-The cat doesn't really impact performance that much so why not be a lil more green and run one?


Now all that said, the catted pipes are more expensive. You do however get what you pay for, cobb and Invidia are nice pieces. I've installed both on various cars and personally have a catted invidia on my 2010 hatch w spt cbe. The cobb dp's will literally bolt right on without any trouble at all and mate directly to the spt cbe. The only catch with the invidia and some others is that they are flat flange type (where they meet the cbe) vs using the factory style donut seal. There are adapters you can buy to mate the flat flange and the donut type cbe together or you can do what I did and double gasket and bolt together.
 

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-You may not always live somewhere that doesn't do emissions..and where you live could always start doing emissions testing. Technically its FEDERAL regulation so could come into effect at any time. Or you could swing better job somewhere else.. etc. Never hurts to be legal.


An aftermarket downpipe (catted or not) is not legal, and never will be. And it will not pass advanced emissions testing.. sorry.
 

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The Fruit
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*most* will.. I happen to live in one and have my car inspected at the dealer. It passes visual as long as it has a cat and the correct verification numbers stamped in.

but this is why you check your local laws first.. which is what I was getting at.

didn't have your coffee today? Dont put sorry after a statement that requires no apology. It makes you look like you're trying to be a douche on purpose.

And if you were, there's no need for that. He asked a simple question and got a simple answer.
 

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Does Eric specify whether you need to run catted or catless like Cobb does?
 

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Not trying to be a douche.. and I'm drinking my coffee now. ;)



It's just that I just explained that catted downpipes are just as illegal as catless last night in another post, and I've probably had to do the same thing two dozen times in the last year. I get tired of people telling new(ish) members to get a catted downpipe because it's legal when that is not true and has never been.

The same goes with saying that buying a catted downpipe will allow you to pass emissions. IF it's advanced emissions testing you will not pass, and I think it's misleading to tell people they will. The thread I referenced last night is even a sticky on this sub forum: http://www.clubwrx.net/forums/engine-modifications/134337510-warning-buying-catted-downpipes.html -- According to Sinister's test it wasn't even close to passing emissions.



As far as legality is concerned, changing ANYTHING to do with the emissions system of a car is illegal, this includes tuning, replacing catalytic converters with other catalytic converters, resistor mods, etc.
 

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Discussion Starter #7 (Edited)
Does Eric specify whether you need to run catted or catless like Cobb does?
It doesn't say on his website, I e-mailed him to check. It just says "Aftermarket DP"
 

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ive heard plenty of people passing emissions with aftermarket DP's
 

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ive heard plenty of people passing emissions with aftermarket DP's


It depends on the type of test being done, and how rigorous the one doing the testing is. I don't have to pass any emissions testing, but based on the fact that my car is catless I should certainly fail visual inspection. However, where I go for inspection they don't even look at the exhaust, all they do is check your horn, lights, and look to see if your CEL is on, if everything works you pass. The place I used to go the guy would pass you even if your brake lights didn't work, he would just say, "you should get those fixed, otherwise a cop is going to pull you over".
 

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^I would say go with the Catted DP. There isn't much power loss through a high flow catted DP (on typical Stage 2 Modifications). However, like it was said before, it is illegal to knowingly remove/tamper with emission control devices.

I have heard of people BOTH Passing and Failing inspections/testing on catted DPs (Depending on location and type of testing, as well as other factors involved).

I still say go with a catted DP, helps mitigate boost creep issues in the 2.5L (YMMV), and is friendlier to the environment (Im no tree hugger, but after running two camaros and a corvette with catless exhausts, I got tired of the strong exhaust odor, exhaust "clouds" and unneeded attention they produced).

As far as emissions testing, my approach would be to keep your stock DP for the emissions tests and swap it in/out when needed (and flash the Stage 1 tune for the stock DP).

You have a 2010 model... Is the waranty still in effect or has it expired?
 

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Discussion Starter #11 (Edited)
^I would say go with the Catted DP. There isn't much power loss through a high flow catted DP (on typical Stage 2 Modifications). However, like it was said before, it is illegal to knowingly remove/tamper with emission control devices.

I have heard of people BOTH Passing and Failing inspections/testing on catted DPs (Depending on location and type of testing, as well as other factors involved).

I still say go with a catted DP, helps mitigate boost creep issues in the 2.5L (YMMV), and is friendlier to the environment (Im no tree hugger, but after running two camaros and a corvette with catless exhausts, I got tired of the strong exhaust odor, exhaust "clouds" and unneeded attention they produced).

As far as emissions testing, my approach would be to keep your stock DP for the emissions tests and swap it in/out when needed (and flash the Stage 1 tune for the stock DP).

You have a 2010 model... Is the waranty still in effect or has it expired?
Warranty is still good for another year or so. Sounds like catted makes the most sense - was hoping to save a few hundred $ to make it a quicker purchase but it might make sense to hold off and get something that will be better long term. I can live with environmental effects but don't like the sound of boost creep. Any cheaper alternatives to Cobb that will work with the SPT? From reading it would make sense to also get a new heat shield as well, correct? I know you can modify the current one, but I'd like to be able to put everything back to stock if needed (and not have it look hacked)
 

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Discussion Starter #12
Does Eric specify whether you need to run catted or catless like Cobb does?
Just got a response from Eric, he said catless DP works fine with his stage 2 tune. I know on my stage 1 he modified it after sending logs, would that avoid boost creep issues? I keep going back & forth on this but am leaning towards catted (rather be on the safe side).
 

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The Fruit
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As far as legality is concerned, changing ANYTHING to do with the emissions system of a car is illegal, this includes tuning, replacing catalytic converters with other catalytic converters, resistor mods, etc.
Correct.. but unless they put you on the rollers or get really stingy about it (aka cali) its likely it'll get by.

legal? No, and you're fully correct by stating that. I should have. Anything other than factory equipment is illegal. However, people will do it anyway.. so may as well go as close to legal as possible.

Sorry about the backlash, I hadn't eaten yet. I go full ******* when I dont eat regularly. lol


In regards to the OP heatsheild question, I've got the perrin unit and I really like it. I did have to trim the inside lower corner off of it to get it to clear the bell housing while mounted all the way forward (gives the best turbo coverage mounted that way) but regardless its a really nice looking and well built piece (wasn't easy to cut through) and does cover the turbo quite well.

Another thing to think about while you're in there is a turbo blanket.. keeps even more heat from getting to that intercooler and will be easier to install while you have other stuff out of the way.
 

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As far as legality is concerned, changing ANYTHING to do with the emissions system of a car is illegal, this includes tuning, replacing catalytic converters with other catalytic converters, resistor mods, etc.
This doesn't apply in the OP's case, but isn't there a clause where certain aftermarket catted systems can legally replace a BROKEN or end of life OEM cat, or did that mean you could only replace broken cats with another OEM one?

Again, I ackowledge that this wouldn't apply in the instance the OP is mentioning, but I thought I remembered reading something like that, but maybe I'm crazy.
 

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Discussion Starter #15
Has anyone on here used the CNT catted DP? I ask because it's significantly cheaper than the other options I've seen and I've heard some positive feedback about it. I'm assuming I'd need the adapter since it says 3" and I'd be goign to the SPT CBE
 

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This doesn't apply in the OP's case, but isn't there a clause where certain aftermarket catted systems can legally replace a BROKEN or end of life OEM cat, or did that mean you could only replace broken cats with another OEM one?


Replacing with OEM equipment is fine.. and I would assume 80% of the people here drive cars that are legally "for off road use only". It's really not that big of a deal, I don't know anyone who has actually got a ticket for modifying their car (although I have heard of cops threatening to make people return their car to stock, but that's usually only if they catch you driving like an ass).


Most emissions testing isn't rigorous enough to fail someone with a high flow cat, but it does happen. Then again, I know people locally here that have passed a sniffer test with a fully catless exhaust. Technically anything other than OEM should fail a visual inspection, but most techs aren't that picky and/or don't even know what OEM exhaust would look like, so as long as it looks like there is a catalytic converter most of the time you will be fine in that respect.
 

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jlinnell98 said:
Has anyone on here used the CNT catted DP? I ask because it's significantly cheaper than the other options I've seen and I've heard some positive feedback about it. I'm assuming I'd need the adapter since it says 3" and I'd be goign to the SPT CBE
Not the best fitment for the one I installed on an '08. One of the bolts on the turbo was too close to the bottom of the bellmouth, making installing the nut quite a tedious process.
 

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The Fruit
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^ I know a guy locally that has a full CNT turbo-back on his '11 sti and he loves it. Sounds pretty healthy too. He didn't mention any fitment issues but since he's only got an assortment of tools that are barely enough to work on basic stuff I'm thinkin his went right on.

Might be something to think about, although the turbo's are different between 08 and the 09+ cars.
 

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Not trying to be a douche.. and I'm drinking my coffee now. ;)



It's just that I just explained that catted downpipes are just as illegal as catless last night in another post, and I've probably had to do the same thing two dozen times in the last year. I get tired of people telling new(ish) members to get a catted downpipe because it's legal when that is not true and has never been.

The same goes with saying that buying a catted downpipe will allow you to pass emissions. IF it's advanced emissions testing you will not pass, and I think it's misleading to tell people they will. The thread I referenced last night is even a sticky on this sub forum: http://www.clubwrx.net/forums/engine-modifications/134337510-warning-buying-catted-downpipes.html -- According to Sinister's test it wasn't even close to passing emissions.



As far as legality is concerned, changing ANYTHING to do with the emissions system of a car is illegal, this includes tuning, replacing catalytic converters with other catalytic converters, resistor mods, etc.
if he lives in a state that doesn't do emissions testing... it doesn't even matter one way or the other. Will it void his warranty? Yeah, if they catch it and are harsh at that dealer. However, illegal means nothing if he lives in an area where testing doesn't exist. I live in Md and as far as I know in Delaware which is about 5 or so miles from us there is no testing and talk about some ****boxes driving around with no muffler or ALL kinds of POS civics with full exhausts that you know have no cat of them. No one cares. They are pretty strict here in Md... so for me I need to get something that I can change back every 2 years. It's a bit of a hassle but oh well. If there were other mods that wouldn't have the need to replace the downpipe and make good power, i'd go for them, but from my understanding the DP is an extremely restrictive part of the cars performance.
 

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Just a heads up, my stage 2 STi (catless invidia) gets some pretty bad boost creep when its under 40 or so. That being said - I just don't go romping through the high revs in freezing cold weather - not rocket science. On the other side of things, I'll probably go with an external waste gate down the road. If cost is a concern, a catted down pipe cost is much lower than a catless down pipe + ewg set up.

Also, I know in PA if you live in a county without emissions, the 'anti-tampering check' gets moved into the safety inspection. Just putting the thought out there.
 
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