BWfVA

Yea I have heard great things about the FRPP Mufflers. The other hand the Glasspacks arent such a good idea. I have heard 4.0 striaght piped and I dont think they sound very good at all and a Glass pack just give a more mellow tune. As for the glasspacks getting louder after they get older, that is true also, even to this day. The glass in the mufflers melts every time you run your car. The longer they have been on there the more that melts and after a while they are just metal tubes filled with melted fiberglass that does nothing. If you want to learn more about them and more about muffler tech one good article to read is the muffler article in Chevy High Proformance they have the Dynomax guy in there talking about all different set ups and how they will affect all the aspects of your car. Just a side note Dynomax also still sells Glasspacks. Its the March 08issure by the way

BobbyRay

They do get louder. Mine were on my 04 for about 3 years and got noticably louder.