Problem with upgrading to a stiffer clutch and leaving stock tranny alone, is instead of slipping the clutch you will be breaking s***. I run a slightly stiffer clutch, but do not want to replace my tranny, it still slips if I try to launch hard. It has slipped since it had 10k miles on it and I was pulling 326whp on stage 2 e85, so I figure, it's either live with a bit of slip or replace the tranny. Given this slip is only at 5k+ launches,and it is now putting down 386 on airboy(low reading), it grabs hard enough to skip the car across the asphalt, all 4 wheels rolling over. If it slips really easily you might just need to replace the clutch?