ORIGINAL: Rockman
Go with the JP2 pipe for more low to mid torque power. The JP1 is more designed for long full power runs. The JP2 is designed more for a track with turns and smaller running area. I put the JP2 pipe on my buggy and it takes off. You will need to cut the pipe hanger wire some to shorten it since the pipes are longer.
Rockman
You have that exactly backwards:
JP-1 Low end, short track
JP-2 High end, long track