Exhaust Question

[Galen]

Hey guys, I'm planing on having custom exhaust made for my 01RS. Reason being, I don't want to spend a lot of money on some "JDM" exhaust when I'm just going to be rompin through the dirt and gravel with it! So, I am planning on keeping the stock headers (they fit under my skid plat nicely) but i want to redo everything from the headers back. Has anyone done this? I'm not worried about noise (Boxer FTW:headbang:) but I do want to be able to pass smog with it, so a cat is a must. What diameter would be best, and are there any good high flow cats out there?

[kreitz3]

2.25" Torque FTW!

[I Like It Sideways]

Like kreitz3 said, 2.25" would be your best bet, for good low end torque, but it won't choke out at higher RPMs.
As for a high flow cat... well I'm not quite sure... I said bye bye to my cats :D
I do believe Stromung and RT both have bolt-on cats... others have to be welded/modified to fit

Check out Boxer4racing.com (http://www.boxer4racing.com) for stromung and RT cats.

[Corruptmotors.com]

we have vibrant high flow cats that flow nice and are rather cheap

2.25 is a great size to go with

[UP2MTNS]

http://www.davenportracingusa.com/flash/

click on products.....misc parts.....2nd from bottom.

[Blix666]

i hear good things about Magnaflow exhaust components. cats/muffs and the like.

[Drew84]

Random Technologie makes hi flow cats.

[lminette]

Problem! Hate to burst your bubble but a high flow cat won't pass smog. It'll make you throw a computer code. When I bought my RS the cat assembly had been replaced with a single universal cat. The car ran super clean during the smog test but the computer recognized that something was up even thought the check engine light was not on. The Subaru O2 sensors have really tight tolerances so if things are off by the tiniest amount it'll not pass. My suggestion would be to have your own trackl pipe made that deletes the cats altogether, hold on to your stock set up, and slap it back on every two years when you need to go smog it.

[Galen]

^^ I was just in auto shop and we were talking about cats. my teacher said that OBD2 cars are very strict with the cat (1%-2% margin) before it throws a code. I thought about using the stock cat, but the piping is so freakin small, it seems to restrictive. I'm starting to like the idea of running a header back straight through exhaust. I think ima use a magnaflow muff. that is like 2.25 in and like 2.5 or 3in out. just one of those oval muffs. with a tail pipe comin out. I had that on my last car and liked how it sounded.

SOOOO I guess, ill run a straight through setup and just store my stock exhaust for smog!

[Blix666]

magnaflow muffler + stock exhaust.

http://myspacetv.com/index.cfm?fuseaction=vids.individual&videoid=10299124

[Galen]

^^ is that 2.25? I think ima run the 2.25 all the way back to a magnaflow muff. like the one above. do you guys think that this is going to be so loud that ima get tickets for it? its going to have a actual muff. on it so i would imagine that it would be REALLYYY loud... I kno that this mostly depends on what type of cop your dealing with, and what mood he is in.

[Blix666]

its the stock piping all the way to the muff...i believe it's 2.25". i've had this setup since June of this year and haven't been bothered by police...i've actually been pulled over with it and not been cited for it. the cop didn't even mention it. but i think it may have something to do with the fact that i had it mounted up and in as far as possible and painted black to look less conspicuous.

[Galen]

sweet, flat black FTW!!!

[lorenkb]

There should be a mechanical fix for the CEL with a highflow cat. At the very least you could find out what the "normal" output of the o2 sensor is and duplicate it. It's the fine line between attempting to appear legal and keeping your car from throwing CELs... FWIW I'm pretty sure messing with the cat is illegal, whether you are removing it entirely or replacing it with a high-flow version... stupid rules :angryfinger:

EDIT: Thanks for that link Jon, those kick ass!

[Anakin_jackson02STI]

There should be a mechanical fix for the CEL with a highflow cat. At the very least you could find out what the "normal" output of the o2 sensor is and duplicate it. It's the fine line between attempting to appear legal and keeping your car from throwing CELs... FWIW I'm pretty sure messing with the cat is illegal, whether you are removing it entirely or replacing it with a high-flow version... stupid rules :angryfinger:

EDIT: Thanks for that link Jon, those kick ass!

it is indeed against FEDERAL law to remove any working cat from a vehicle...

[Galen]

yup^^ just talked to a guy, he said he could make it with brackets, than bolt up the stock cat, than make me a test pipe so that i could put it on myself... but he wanted way WAY to much money. I know a place that said they would do a whole exhaust system for $150 (not including muff. cost). hmmmm, wonder if you could get them to make exhaust, than install the stock and just give you your exhaust to install your self?...

[409industries]

Thats funny because my RS just threw a P0420 Code a few days ago. "Catalyst Efficiency Below Threshold (Bank 1).

Which is a bummer because id like to know i have a functional cat for smog time! A straight exhaust with a magnaflow muffler would be the way i'd do it.