I have the turboxs catless downpipe and racepipe which attach to my JIC Bullet 505s full titanium catback. It sounds great. With the silencer in it the exhaust sounded stock but when I took it out it sounded really boxeryish. Pricey though. Ran me around $1800 for the set up. But I like the idea of an 8lbs catback. Weight reduction is almost as important as hp gains to me. STI is way too heavy. Need to get it down to around 2,900lbs. APS is producing a 3.5" stainless steel turbo back exhaust. I'll post a link to it below.

-Money Verone, That's weird because I have an 04 STI and I don't have a cat in my uppipe. I had a cat in my downpipe, one on the cat pipe (after the DP) and of course a resonator in the midpipe. Take the heat shield off of the uppipe and take a look.

As far as gains go, when you first get a car the best thing you can do is "air-in, air-out". For a turbo car though, you have to watch out for the air-in part. Too lean is bad and can produce detonation. Good gas milage though. But realistically I wouldn't expect any gains from an exhaust to exceed any more than 15-20hp. On the high end if you remove the cats. The exhaust isn't magical pipe.
Here's that link, also included is the JIC link of what I have if you're interested:
http://www.aps-wrx.com/us_spec/subar...wrx-hoe-r6.htm

http://www.aps-wrx.com/us_spec/subar...wrx-hoe-r4.htm

http://www.vividracing.com/main/
go to go shopping, 04 WRX, engine, exhaust,and there it is and there's a dyno graph there too.

 

i say buy a downpipe and weld the rest and use alum

 

Have ne one heard nething about the gram lights exhaust for the STi?? I love the unique tip design, but I need to find out specs, sound, and power gains with that exhaust. Neways I found this pic of the tip on a evo:

http://forums.evolutionm.net/showthr...threadid=26440

Also is everyone talking about the Ti STi exhaust or just the one with the painted sti on the tip