Everything you need for big power and performance gains packaged in a single part number… Zipper’s Performance has done all the engineering for you! The Zipper’s Muscle 103” Kit is an easy to install kit that produces outstanding results while maintaining Zipper’s legendary commitment to engine durability. The Zipper’s Muscle 103” Kit is designed for use with high octane pump gas and transforms your stock 96 or 103” Twin Cam® engine with a smooth, linear power curve you can feel at any twist of the throttle. This kit is a “drop on” package, and comes complete with Zipper’s high flow CNC-ported head machining, precision cylinder boring and honing with forged pistons, Red Shift® performance cams and dual-piston cam chain tensioners, ThunderMax® EFI with AutoTune and MAXFlow air cleaner assembly. ZippersPerformance.com