I'm getting 3.90's put in this saturday. I was thinking about 4.10's, but i am thinking ahead for when i get my procharger by the end of the year, and i dont want to run out of gear at the track. I was doing an online gear calc. and it said with 3.90's and 6k on the tach, i would be trapping right at 120mph with my 18's. Is running the rpm's to 6K bad? Or is it ok to do at the track every once in a while (1 or 2 times a month)? Also, what is the average a 2V with bolt ons and a procharger trap at in the 1/4? I am hoping less than 120mph so i dont run out of gear even with my 3.90's.