cruzmisl

I had my muffler changed due to a rattle, and now there seems to be a vibration noise when I get on it and go WOT. Pretty much the only way I can get it to make that noise is to be aggressive on the gas and get past 4k rpm. Is there a common source of this noise? Does anyone know what they have to remove just to replace the muffler?

Just wondering if I can source this myself or have to bring it in...