I ran the JP-1 on my GRP for about 2 gallons. I could easily go ten minutes until lately, it dropped to 8.25 at columbus. I did not change anything, and the motor still runs the same temp as it did when it was new. I went to the JP3, and everything was WAY OFF which shows that their is at least gain or loss to be had from changing the pipe. The only way I can explain the difference between the two pipes is that, the JP-1 is a pipe to use with a extremely hyper, unmanageable engine-indoors (with one exception). The JP-3 doesn't seem to be more hyper or "hit" harder as much as it seems to run cleaner and be more predictable.

The exception for the JP-1 is it seems to run well on junk motors. I have ran a o.s vg in a buggy at JCP(huge outdoor track) and a truggy at planet RC (high grip-good sized indoor) and tried both pipes. The JP-1 ran better and ran longer. Not to say that I was racing against stacked fields but I won both times, when I was merely running a joke of a motor to make laps. The pipe was a big difference especially in a 30 min. main such as the case with the truggy. It seems absolutely wasteful on a good motor.

Hope this helps!~