>> One of the things I don't understand is how the RX-7s just go faster and faster

Perhaps I can safely say this in the P-car forum without being run over.

I've had guys come up to me and tell me how easy it is to port the RX7 motors slightly to get big gains. Oh and then they go on to say how no tech inspector will ever see it... It's actually weird how many times I've been told this. Now, I have no experience with rotary motors, but if this is true, it may explain how some RX7s continue to go faster. You know, kinda like when all the Volvos stopped braking valve springs and started going faster as a result. :P