Here is a couple examples for you all to chew on. The heads up car we leave to 38-4400rpm on the brake. It is adjusted to make up for driver reaction time, he dont race much. Car has been 1.09 60' converter stalls at 9200 rpm! Higher has done nothing for anything but reaction time on a .400 pro tree. I found the same results with our dragster and the Stratus, 1.02 and 1.00 60'. Since we both leave off the top bulb on a full .500 tree we are both at 4000rpm. Nothing found going higher in RPM on either car other than more delay. But as I said t is very combination dependent. HP has a roll to play here as well. FWIW both the latter cars have converters that stall at 65 and 6700. My 64 we leave at 3900coverter stalls at 6600 and the 60' SUCKS but we are pulling alot fo timing and they click the 60' clock with the back tires...But it helps me with the bottom bulb for sure.