Recently bought a DC ceramic coat 4-2-1 header for my 97 GSR and there's a very small HIGH PITCHED whistling sound when I hit the gas. I cant seem to locate the origin of the whistle, but theres not holes or cracks in my header. I did reuse my stock exhaust manifold gasket, it didnt look worn or thin at all.. looked exactly like all the ones i saw in car stores.. I think it may be the donut gasket but I'm not positive. Everything is tightened and the sound is kinda annoying.. anyone else have this prob?

 

I have that exact same problem.

I put a DC 4-2-1 on my teg, and it whistles at the donut. I havent really had the time to fix it yet though.