Im running a 370hp small block pushing 5200rpms...I had them and they take the harsh sound out and give it a nice mellow sound(if thats what you want) I thought they were a good deal until I tried taking them out. Per GPS I gained 1.5mph Put on a pair of Shotguns and gained .5mph over open exhaust....All of this was verified per GPS on several runs on the same day.....If you are running a stock motor the slip ins are great. If you just forked over a wad for some HP don't even give them a shot. I prefer the shotguns....If you take the time to adjust them properly they are awesome.....

BH

Thanks, I look forward to your results. I need to buy a set for my AT and GGB are relatively local to me.