what engine do you have or putting it on? that will tell you more.... my JPX gets more power and run time running the JP3 but WS7 gets better run time with JP1. its all about the engine. its all what you want, driving style etc, no one can tell you the right pipe for all engines, the pipe that works on one engine might and probably wont work on a different engine.

these are the engine pipe combos that worked for me:
Alpha engines - alpha 0801 pipe
GRP - 2053 (i think)
RB C6 - RB 2045
JPX 21 - JP3 or RB 2045 (for smoother power)
OD SS 21 - JP3 (for power but only 7 min run time) and 053 for 10-11 min run time


right there kinda shows that you cant get one pipe to fit all engines. the dynamite 053 always seems to get the most run time but some engines it doesnt get the power i need. the JP series are good pipes, the JP4 seems to be the best all around pipe for power and run time tho. the JP1 and JP3 seem to suck the fuel compared to JP4. IMO if you want a JP pipe get the JP4