i tried jp3, 9901, 2013, bullit 1005(oh yeah i got 1 of those)... on the track i was running on i prefered the 9901 with the jp 3 running a close second... the 9901 allowed me not to have to much wheel spin and all the top end in the world and then some... i'll tell you what this engine screams... oh yeah and the 2013 would come in 3rd.. 1005 was ok.. but it lacked something.. i only noticed it when i tried the other pipes.... seeing that was the first pipe i tried...