While I don't disagree with the suggestion of using a werks pipe, I don't know why people say that the jp pipes get bad economy -- the jp-4 got excellent economy on my v-spec. I have taken it 10+ min on my v-spec in a main on small tracks and never had any issues pushing out to 8+ minutes on the v-spec on large outdoor tracks either.

Did you have bad luck with a JP pipe for fuel economy?

I too had also heard that the JP-4 was bad for fuel economy, both on the internet and by word of mouth, but I talked with one of their factory team drivers about it and he said that the jp-4 should get better, not worse, economy than the rest of the jp line. I have to say, I was pleasantly surprised that my experience agrees with that.