ok. I have a 04 type-s. mods are injen CAI, Strup race header, 2 1/2 in exhaust. the car hisses from 1000 rpm to 4000 rpm (cant hear after cause exhaust is loud) I have had it checked out for exhaust leaks 4 or 5 times already. the shops (diffenrent shops) say that my header or exhaust arent leaking. WTF!!