to allow the engine to rev quicker, but as you noted, much more driveable off idle. Got a question for you: I drag race my Z (at least I have in the past and had the car built with drag racing in mind). How does a heavier flywheel (a lightened stock unit of ~18 lbs compared to ~12 lb aftermarket one) translate into getting the car off the line (ie. 60' times)? My (non-professional) thinking is that the initial "hit" is harder and gets the car moving quicker, but as soon as the engine starts spinning, I lose some of the quicker revving derived from the lighter flywheel. Any thoughts?