Michael,
The JP-1 and JP-2 pipes are nice. I ran the 1 on my M2K and a buddy ran the 2 on his Hot Mod P5. Both engines were screaming and running around 220-230 with about 1/4 of a tank after 5 min. qualifiers so they seem to get good mileage also. One day when we get a chance to get out to the track and goof off a little we plan on switching them back and forth to see how they do.
As far as the XB8 is concerned, I think I'm going to like it alot. I didn't get a ton of run time on it but during practice I would run a tank of gas, bring it in, change something, put it back on the track, run it, change something, etc. Small changes are noticeable. There are so many adjustments that can be made and having the manual hand is really helpful. It feels good on the track, handles jumps well, reacts quickly. I know alot of it is in the setup, but I'm not far from stock setup. Planning on taking it to a different track this weekend with a completely different surface to get a better idea of the buggy.
FWIW, I got mine off of ebay also.
Also, if you compare the Jammin pipes to the Picco pipes you will see they are very similar. The JP-1 is appears to be exactly like the Picco 069.