The downpipes don't make them louder, IME. I even changed out the resonator for a smaller one and it didn't change the sound at all.
It's not quite a miracle drug, but it's close. Allows me to run a 3.2 on a top swap. Converting is really easy. It's better to tune for it, IMO, but you can just switch to 42.5's, get rid of the gasoline, put E in it and you're good to go, maybe a filter change pretty quickly.