I'm currently running the Summit bullets. They keep my car legal (I'm pretty sure you must have mufflers to pass inspection here in Texas, which they *technically* are), and they don't choke up the exhaust at all (yes, you can see straight through them). They may quiet up the exhaust a little, but not as far as I can tell.

"When I'm in a slump, I comfort myself by saying if I believe in dinosaurs, then somewhere, they must be believing in me. And if they believe in me, then I can believe in me." - Mookie Wilson