Cylinder with piston kits include fitted pistons and cylinders, head gaskets, base, and exhaust gaskets Cylinder kits with pistons are honed to fit the pistons included Pistons are dished dome design intended for use with stock cylinder heads The cylinders are machined with the stock bolt pattern and are intended for use in stock crankcases of 1999-2006 Big Twin engines. Designed replace cylinders in 124" or 111" displacement Hot Set Up kits Cylinder finish is a durable wrinkle black powder coat or silver For best performance, appropriate camshafts, performance air cleaner, performance exhaust and fuel system tuning are required Crankcases must be bored to accept the larger 4-1/8" cylinders.