i have searched on the board for similar problems and only found one thread that appears to be the same problem. in my GS-R coming from the engine compartment is a rattling between 3-4k rpms. i have tried removing the heat shielding on the exhaust manifold to no avail. in the previous thread on this topic one person seemed to hit it on the head by saying that between 3-4k rpms is which the engine produces most exhaust pressure and the rattling is due to a cracked a-pipe within the exhaust manifold.
i just wanted to refresh this topic and see who has similar problems because this is a problem i have had ever since i got the car at 88k miles and i am really looking to fix it. i dont think it has anything to do with the cat since its coming from the engine compartment and not from under my feet. if nothing else i think i might just pick up an exhaust manifold for a b18c1 from a junkyard or something and stick that on there. anyways, lemme know what you guys think about this and who has had similar problems.