Thank you mate for sharing your experience.
I was also aiming for the 3,9:1, so that will be the choice
I am also running appr. 6000 rev in 4th but I can not get as high as 120 mph I did best only 111 mph, what power ratio are you running? And what time did you get at this speed?
I have also tried bigger tire, but my biggest problem have been the start, far too much wheelspin and the 60 feet time just about 2,3 sec.best.
There are many discussions on whether to warm the Toyo R888 before run or not, have you any experience on that?