I've used them and love them. Similar in design but a fuzz cheaper is the Magnaflow welded mufflers. I've got a set of the Magnaflows on a 440 now. The mufflers are right before the axle and then I have a small set of Summit 14" long glass pack style mufflers right before the turn downs at the bumper and it sounds great. It has a great low rumble at idle, a mild growl when you get in the gas a bit, and then you know its got a 440 when you romp it.