Hey guys, so I just bought a 2006 STI with the following mods:
-forged pistons and slight bore
-AEM CAI
-FMIC
-garret gt30r
-tial 44mm EWG w/ dumptube
-750cc RC injectors
-aftermarket fuel rails/lines
-invidia DP
-tomei EL headers
-HKS carbon ti catback

It currently puts out 316.5 whp.

I want to run a stock STI axleback permanently because I hate being loud and obnoxious.
Is this possible without jeopardizing the reliability of my car?
Thanks in advance!

 

Might I suggest going with 3 inch piping all the way back to the stock STI muffler. I have heard of others doing this. You can also pick up a quiet full 3inch cat back that still allows your built motor to exhale like it should but maintain a quiet and stock appearance.

You should take a listen to my exhaust it might fit your needs.

 

Have you considered a maddad whisper? They are quiet and still perform well and look stock. I wouldn't run any exhaust less than 3" if you want to keep those hp numbers.

 

you would need to retune and loose about 30whp, do what i did and go with a maddad whisper it looks stock and is not loud

souns like you got one hell of a car, please post up some pictures

 

Don't care too much about hp numbers, I just don't want it to blow up my engine or anything. All the piping is 3", except the sti muffler, which would be 2.5".
Am I able to do the swap without a tune?
Would it increase my EGTs and burn out my o2 sensors?

 

You have a built motor and a pro tune, why would it blow up? Seriously, I would not run a 2.5" exhaust, you will choke the **** out of it. Any 3" exhaust with a non fart cannon exhaust will be fairly quiet during normal driving. I'd consider the borla hush or maddad whisper if you want quiet. You can just swap anothet 3" catback on without retuning. Its just my opinion, its your car.

 

Did you have the exhaust piping change on the stock STI CBE you picked up from me? If you didn't then the piping is 2.5 in i believe not 3.

 

Currently, I have no stock exhaust components on the car. All aftermarket.

 

I have the Greddy evo 2 and it's very "quite" compared to the angled can style exhaust. My buddy has just a catback with everything else stock and it's louder than my car and I am fully catless with aftermarket headers lol

 

I highly doubt using the stock can is going to effect it to 30whp, our 2.5inch tapers to like 2" at the end of our legacy's negligible difference on a dyno, ask Mike at GST he can give you a straight up answer on that one. If stock STi is that restrictive or not. On top I highly doubt a retune will be needed unless its a very agressive tune. If anything run a midpipe resonated that mates up to your stock can.