OK the thing is l have a subaru sti and its completely stock and a wanna put a cat back and a downpipe but for the downpipe l have to buy a reflash or something or to tuned it a little bit because l heard that you could damage the engine or you just buy and installed it and that is it ....hellppp!!!! 10 points!!!

TALK TO THESE GUYS MY FRIEND BUILT A TARMAC CAR DEALT WITH THEM A LOT. THEY KNOW YOUR CAR.

http://cobbtuning.com/

no reflash is needed to do turbo back exhaust (down-pipe, high-flow cat & cat back system) No engine damage will result from a down pipe or any other post-turbo exhaust changes. l had full exhaust on my 02 wrx with no reflash. (header, up pipe, down pipe, high-flow cat, cat back.) & only had power gains. as long as u still utilize ur o2 sensors & have a cat u should not throw any check engine lights. u do need a reflash when u intstall things like larger injectors, larger turbos, MAF sensor cylinders, cams, boost controllers, etc. Exhaust, especially after the turbo, is a very basic mod & requires no computer trickery.

l have told u already. It is different for 02-03 WRX is because they do not have the complicated open loop/closed loop mapping of the ECU is from 04 & up. So u will have boost creep & u will damage ur engine but listen to roost4 if u want but in the end he does not have to write the check if something goes wrong. Plus he says hes a tuner but has no idea about cars other than his so his sources r meaningless. l am telling u if u have a cell phone call one of the tuners l gave u in my last answer & give them a call. Most cells have free long distance so it wo not cost u a thing & u would have had ur answer by now. Believe me buddy, l am just trying to give u info so u do not do damage to ur baby. l will even give u some of the numbers if u do not want to look them up.

Perrin performance is (503)-693-1702

Rallitek 1-888-7731212

Cobb Tuning 801-713-0035

Just call one of them & get the truth from them.