i figured they were all bout the same. i found out with gen 1 Q pipe i got for my old zilla you need alot of motor for an xpansion chamber that size so i'll have to pass on $500 for "drag" pipe again. (bigger isn't always better) at least in my xperiance
depends on your type of riding as well, high rpm type of riding favor that type of pipe, ask anyone here that runs the pipe. slow speed riding or snappy throttle response will favor a different pipe. so if you are looking for an improvement, be more specific, ie type of riding or goal of bike. west king is right, if you want to make more hp, the shearer pipe is going to be the way to go, also its not a drag pipe. the other pipes mentioned are really close in performance so that is on you if want to change.