Ok, I have an update
Tried launching a few more times today, best run was 4.59. Did a few things differently this time. This time instead of shifting at around 6k to save the engine, I let it rev out to redline and autoshift, that means that the entire launch to 60 is in one gear, so we can rule out shift times. Also hit the gas a little harder after letting off the brake, though the traction loss if you over-torque it still raised our time on a run or two, I'll have to get a feel for the right amount of power to apply. There was also a hundred or a hundred fifty less weight in the vehicle (discarded the body when I realized I no longer needed it to weigh down the back end after the RSFB upgrade). I bet I could get even lower times if I throttled it perfectly. All in all I'd say I'm very satisfied with what the car is doing now, I'm probably the major limiting factor, need to learn the proper technique to maximize times and all that
