Does any one know why test pipes are so raspy sounding? Is it because there is no insulation on them? The thought crossed my mind to maybe thermal wrap my test pipes, to give them kind of an insulation. Has anyone tried this? Do you think it would reduce the raspy noise?

 

i tried it & it didn't help!

 

The test pipes allow resonances inside the exhaust system to become active. Thats why the rasp happens only in certian rev bands. Something that changes the resonant frequency of the exhaust would help alleviate the rasp. I have considered altering my X over on my borla to see if I can affect the rasp.

 

Dont waiste your time with the test pipes. not only is the rasp bad, but the smell. I would spend the extra money on high flow cats.