the softloc, will slip enough to let you use aluminum flywheel , even on street! a rag disc and more pressure does not!! mcloed flat said, aluminum flywheel only, the cluch gets hot and will grab so hard and be very jerky. there's a reason why they want you to use their setup. less problems and comebacks. all my cars have had aluminum flywheel on the street, had no problems driving them. even had one behind a 265 chev in 55 chev. with a 3000# clutch!! very old school back then , 1965. like anything else, you learn how to make it work correctly.