harley davidson jets

2>1 YUK theyr great on a "bagger"like wagonmasters but "SPORSTER"means just that torque cones are a restricter that is at the head end of the pipe lets say you have a 2" pipe they weld (or slip) i where the pipe goes into the head at 1 3/4" creating sort of a Dam so pressure comoming back up thru the pipe cant be sucked back into eng..keeping everything(ex gases--unburned gases etc)flowing OUT and clean gharges IN i DO know they greatly increase the low end torque (sometimes)lost by open style pipes but w/ a pipe at least 18"long they sound good(i use removeable baffles frreflow ONE direction)low end throttle will more snappy no gurglin at mid(if correct jettin)and still great pull at wot do some research drag pipes or mufflers are all about WHERE youl be running most longer 3''off 4>1 collecteor on a small block does NOT run the same as say a440 then for a comparison put a 4bbl k&n -headers-then a 24"long stock Cbody muffler DOG change Mffler to a 2 1/2" Borla or flowmaster and wake eng up