I'm considering doing a catted downpipe on my 2004 STi and would like some opinions on whose is the best.

Let me say first, I don't really care about price. Spending an extra $100 to have something that fits well and doesen't leak is well worth the investment.

The downpipe will be catted, I don't want to deal with the smog ****'s every couple of years. I need something that will look... well like it's supposed to be there. I want to avoid wraps and would rather get somthing cast or ceremaic coated.

It looks like Cobb and Maddad make the best units out there, with Maddad maybe winning on design with their bypass tube for the BOV.

This will probably be mated to the stock STi exhaust and I want to keep the car quiet and it doesn't seem like there is really any benefit to a cat back from a power standpoint.

Educate me... what's the best
Am I missing anything?

 

I have read pros and cons with the Mad Dad divorced wastegate design and how it dumps the wastegate gas past the cat. What about the Perrin 2 piece dual cat DP? AVO makes a DP that has a carb approved hi flow cat on it as well.

 

Too bad avo is so dammed expensive.

Im a fan of the one piece dual catted maddad. I still don't trust perrin but it seems like a nice piece. 2 parts like stock so figment should be easy.

 

E: nvm irrelevant

 

one thing i would note is to check both the flanges on each, donut or flat? so that you don't have mating issues to your stock sti cb.

i think the cobbs are donut and the maddad is flat and i think your stock sti cb is donut, so if you went maddad, you're gonna have to cut/weld something i think.

note though, that either will probably NOT look like their oem, that's for sure. the perrin one has a perrin logo welded to it, right where you can see it, and it's nice and polished.

 

I'm running the perrin 1 piece catted divorced, and it's been good so far. nice piece. mated to cobb cb

 

Never heard of AVO before... but I'm interested.
Anyone got a website for the actual company?

 

http://www.avoturboworld.com/avoshop/

Yes, I'm looking based on this thread I'm in the same boat as you, looking for a catted DP as we speak.

EDIT: Not seeing anything about CARB cats, you would think that would be a huge selling point.

 

I am telling you nothing you don't already know, but quality of the maddad is amazing. It is well constructed, had no problems at all while I ran mine. I was actually going to try and pass smog with it, just never had the chance. Mine had the wideband bung in it which made tuning convienient. Can't say anything about the cobb since I never had one, sure its a decent piece too.

 

Sooooo bummed I couldn't get that.

 

Are the Cobb and Maddad smog legal?

 

Technically no - they don't have CARB EO's
That's why the AVO has my interest peaked.

CA rules for Cat's are strange. Technically the car has to have a certain number of miles on it to legally replace the cat.

 

Everything I've read says no. Maybe they'll pass the sniffer and no one will notice, but anything beyond a stock cat is illegal unless you have a failed cat and your exhaust shop goes through a whole process of documentation during replacement. Even if that happens no aftermarket DP is CARB certified, so they're all illegal.

 

The Cat is C.A.R.B. Approved, but the whole downpipe is not.

http://www.subimods.com/avo-3-downpi...t-5mt-6mt.html

I just got the AVO Downpipe and you can see pictures of what it looks like along with pictures of it installed. Honestly, this is about as stealthy a downpipe as it really gets when looking from the top down (not from underneath).

However, it might be extremely difficult to find another one as AVO apparently decided to no longer make this particular downpipe due to lack of interest. I got mine from Rallitek. Subimods has it posted as well, but not sure if they can still get any of these.

http://www.subimods.com/avo-3-downpi...t-5mt-6mt.html

 

Dude - that is SUPER stealthy... I could hit the rest of the pipe with some Flat Gray hi-temp paint and no one would ever pick that thing out.