Black wrinkle painted aluminum cylinders. Fits stock 88" models with stock 4" stroke. Bigger is usually better when it comes to performance. This bolt-on big bore Sidewinder kit is as big as possible; without requiring additional work. No need for engine removal; splitting and boring the cases or even re-balancing the flywheels. Just swap the stock cylinders and pistons for these S&S 4" big bore parts and you''re ready to rock with 100HP! (note). Note: S&S measured a 72.95 to 100.30 HP increase with for a stock 88". They additionally used S&S 585 cams; Power Tune headers; slip-on mufflers; the stock EFI throttle body and a S&S Stealth air cleaner. Note: Not for use with S&S 79cc cylinder heads.