i just want to clear up one thing, by no means do i think the Alpha is the fastest or anything, its a great engine, i run the green head im my truggy and dont struggle for power at all, i have hardly any wheel spin if any spinning at that mater. but the JPX is crazy fast. i have yet to drive a engine as fast as it (stock engines that is). however i havent ran a B5 or B6 so i cant say much, i was just speaking from watching them compared to others.