i dont know to much about bottom and top of the motor but do know how it works. i plan on getting the book, thanks BTW. i was wondering if anyone could give a ball aprk figure of how much im looking at on building the bottom of my motor so i can run higher then 10psi. this wont be for another year but just wanted to know what im looking at $ wise. i hear people pushing 25psi which to me is nuts but i was thinking something around 15-20........just throughing out #s though, thanks