Silly rules!.......
The trouble here is the rules he must follow. The only Jammin pipe that he can use is the JP-4 and the RB 2045 is rule compliant also. I would stick with the RB pipe and tune for clutch and gearing. Run the long header if you need more bottom.
On my S7 I get right at 11 mins per tank with the 2045 and it seems real good to me. Damn rules!
If your club will allow it, the JP-3 will give you more bottom end than the JP-2.
Let us know what you find.
TEX