Hmmmmm, I thought Thunder Racing got their cams from Comp. I know they are ground on TR's specs. Maybe TR saw that with the final amount of lift they were specifying it wasn't high enough to change the base circle yet. I have seen guys running almost 1.000" lift on their drag racing only LS1s. If they didn't change the base circle on one of those they'd definitely would either have to increase the cam bearing bore size or reduce the base circle just to install the cam. Those extreme lift engines most likely don't have the cam blank like ours that have a hole drilled all the way through it for lightening.