So I just bought a 2014 Silverado 2500HD. The exhaust is not too bad, except under certain conditions. It's like a window that I can try to avoid depending on how much gas I give, that is really an annoying decibel. Low gas it's fine, or if I floor it I can go right past it, but there is this middle level that is bad. I did some research and this might be droning. But I really am not certain.

Anyway, is this an indicator that my exhaust is aftermarket? Can I add something relatively simple to install that would help keep the noise down? This is my daily driver, plus it's our families horse hauler, so this noise is troublesome.