Yeah my wife has an 06 Impala SS with a DOD 5.3l. We put a 3in catless downpipe, 3in exhaust and some race flows out the back. Before the DOD was disabled it sounded like pure crap down the highway when the 4 mode kicked in. Im talkin bad like a redneck, glasspacked 80's model ford with half of the plug wires working. lol Not getting bad mpg's either. It changed a lil but its worth having the extra power and good sound.