Hello, I love my lightened stock flywheel, my Z is a 1970 with 2.4 bored .040, E31 w/ 280z valves, 480 lift,280 dur. bumpstick, twin stock carbs, 3.90 rear end, early 280Z 5 speeder,headers,2.5 inch freeflow exhaust. I believe that the stock early flywheel is 22 pounds, had it shaved and now it weighs 16 pounds. Had it weighted at the machine shop. A lightweight flywheel is not worth the time or money if you don't like a racy feel and if you don't like to get it on all-the-way and really drive it. I'm not saying U always have to drive like that all the time, but it's a special feeling when I want to drive it that way. And I positively Luv it. Going thru the gears is much better, you can feel the engine rev faster at all points on the tachometer, all the time, it's great I enjoy burning rubber too. Less time spent accelerating the motor means the engine is revving higher and faster and that means seeing Higher horsepower in less time. There was an article in Circle Track documenting the effects of lightened parts in a motor,like a flywheel, they even prove how this can be calculated in actual distance, actual distance your car could be Farther down the track in the same time. My Motor seems to be Happier revving it's little heart for me. The motor is less burdened at higher RPM's. We are talking about Inertia and anything you can do to make the engine change rpms faster is good. Incidentally, my Z has the early lightweight crankshaft (has been know to fail at revs over 8,200rpms) and you know what, they had to shave the counterweights to balance the motor. Pity more weigh came off the crankshaft, cuz now the rotational weight is less. Heck, I rarely spin my Z over 7,000 rpms. just once spun it up beyond 7,600 rpms, and it felt fluid , like an electric motor. Also, need to say I got the Nismo competition lightweight single groove steel front pulley from Rebello. Even that little $120 piece makes the engine rev differently, rev better. Trade offs: In the beginning, the take off is a bit tricky, but you get the hang of it and learn to press down on the gas pedal a bit more. Be a learner not a moaner, adapt and enjoy the pleasure. Tach it up and let it out, feel the power. he he he . I'd love to have the HKS 10 pound flywheel or the Tilton piece, heard it's a jewel.