I am on the verge of buying a 2004 sti from a main dealer. 16000 miles with aftermarket exhaust not sure what make, air filter which looks like a pipercross viper and a blow off valve. when i test drove the car it seemed to hesitate when setting off, normal driving seemed fine. I noticed the idle was alittle shakey when i glanced under the bonnet. Is this anything for concern and is there anything I should say to him as I am going back to look again?

He said can put standard filter and dump valve back on but not exhaust.

 

it could well be the dump valve m8. try the standard one on it.

stew