Gearing also plays a big roll, trans and rear gearing. If you have a glide they usually dont like having the RPM dropped down so far, why you hear S/G cars at or above 6000. The more mulriplication you have at the hit the more tolerant they are of lowering launch RPM. The heads up car had a 2.24 first gear and 5.14 rear gear and a 29.5" tire, alot of SLR.