I am not sure which Pypes you heard but mine sound bad @ss. I get constant thumbs up on mine all the time. Maybe the headers make a difference but I would not change a thing.
I know it is very subjective but for the money I think they sound great.
2007 GT Coupe, Auto, Black, Dark Charc. Leather Interior
Mods: Exterior:18x9 front 18x10 rear DD Chrome Bullitt, Nitto 555's, GT/CS side scoops, CDC Classic Chin, Clear Side Markers Exhaust: Pypes LT Headers, Hi-Flow Cats, H pipe and Violators Engine: C&L Street (Chromed) w/ Brenspeed tunes, Chrome Valve Covers, MWG painted radiator cover and extensions, Custom polished/engraved strut tower covers, Chrome fuse box cover, billett fluid caps