Today at the ODR autox I ran my 91 civic si for the first time the car handled very well but there is a strange whistle under aceleration. I have a cold air and header everything else is stock. Has anyone else had this problem? I dont think its the belt. Oh yeah it happens at 2k rpm and then it stops and comes back at 3k rpm.

 

your intake? check the clamps

 

that could be a million things, i would check intake, and anything around or in the engine bay that could vibrate or that could be loose... most likely what crate said tho..

 

could just be the way your filter is? mine whistles loudly and it's perfectly normal.

 

mine whistles under acceleration too. I think it's normal