Hey guys, right when vtec kicks in i get this nasty raspy rattle comming from somewhere in the engine compartment. Everything is tightened down and no heatshields are loose. The cat isn't broken because ive tried two (first one was and then i got another one which wasnt broken). There is also another one from about 3000-4000 when accelerating and decellerating, along with free revving. My exhaust setup is a JDM ITR header, JDM ITR cat, and Apexi N1 exhaust. The header was bought brand new but about the only thing i can think of is either a defective header internally or the donut gasket (which was also new) might be bad. Ive checked under and above my car numerous times trying to figure out where it could be comming from but can find anything. Anyone have any ideas?

 

You probably have an exhaust leak somewhere. A good muffler/welding shop will check/repair this for $10 bucks up, depedning on how bad the leak is.