This .030" -3.5 degree offset flywheel keyway advances ignition timing for increased acceleration and horsepower. This keyway works excellent in drag race application on any Ski-doo 600-800cc ZX, REV, including 800R, 800 ETEC, and 850 ETEC
motors with good high octane fuel. The more advance you run, the more octane you need to prevent detonation. We do not recommend this keyway for trail application.