um you might want to post this in the STi powerplant thread, but i'll help you while I'm here, just get a catback exhaust you'll notice some better sound, also the Blow off valve will make the psshhhhhh (pressure release sound) when you shift on boost, pretty cool stuff. There is a good video of the exhaust sound on www.hksusa.com that where you can hear the sound of the exhaust and also the bov too.

 

go with a TURBOXS TBE and ecu, the dyno numbers on their site say 318 bhp, 320flb torque, super quality, it's the only way to go.

 

I like my Invidia cat-back great deep sound and only real loud under WOT but if you want the turbo lag to be gone or less apparent then go for a turbo back if you are worried about boost creep just get a DP with a high flow cat and you should be ok on my STI i have XX-Tunning header/up-pipe combo a helix DP with Cat and invidia cat-back i love the sound it sounds mean as hell when i go WOT plus it doesen't burn rice like most other Cat-backs that iv'e heard just sounds like pure raw power.

 

I say wait until greddy releases the full titanium catback

 

they aren't making one ne more

 

since when?

 

is the stock exhaust 2.5?

 

If you replace the downpipe removing both cats, you will hear a throattier sound from the stock cat back. I have mine with no cats and stock cat back, it has a very low rumble and it gets louder as you rev higher.

My car could be louder, but I think this is as loud as I want it.

-GDO

 

If you want the best headers go maxim works best exhaust go fujitsubo cusco jdm bellmouth and prt an polish waste gate so u get no boost creep fujitsubo make best power best quality and not to loud if u go equal lenght header u will loose the sound of the boxer i did i like 2 be diffrent because i sound diffrent i get more attention from suby owners good luck

 

Perrin Dual Tip. Keep it a sleeper!

 

^what he said