The only negative thing I think it did was make my exhaust sound louder in the cab at certain RPMs.

I was more interested in reducing a nasty harmonic from the rather loud exhaust system than I was in making my "audio system" function better, but it's the same idea

I have loud exhaust any way, but it seems like now at around 50MPH and approx

I have a sports car with an aggressive exhaust system.

My exhaust was way too loud

I purchased this to line the outside of a wooden box I built to contain a Bitcoin miner, as well as to line both sides of 5/8 inch plywood before attaching to the walls and ceiling of the room the fans blow into