Kevin, in the u-tube videos I have seen, I'm pretty sure those engines that were turning up over 7,000rpm, were destroked. I tried turning one of my 170 engines to 7,000 at one time. (had a deep 1/8 mile gear, and ran 1/4 mile). Car didn't run any quicker in the 1/4 then with the 1/4 mile gear. So wasn't worth the additional beating.