I originally used these on a 1973 Ford F250 with a 360 FE big block engine mated to some long headers. I wanted a nice loud rumble at idle and they didn't disappoint. I ended up replacing those double glazed windows with standard mufflers just for comparison. The mufflers sounded a little better (louder) at idle to me, but for others this might be the way to go. Nice soft rumble at idle, not enough to wake the neighbors but gets nice and loud at higher revs if you have room to switch on.