I can positively assure you that the dynomax race magnum bullets are going to be way louder than the glass packs even after "glass pack break in" as said before they are supposed to be a race only muffler but I have ran them with a 3" straight through exhaust with headers on my 68 Goat for about 3 years now and they are a bitch to drive when its late at night because you attract that unneeded attention.