Watch Your Riding Buddies in Your Rear View Mirror with the Zipper’s Muscle 103” Kit for Harley-Davidson® Twin Cam® 96” Engines!Everything you need for big power and performance gains packaged in a single part number… We’ve done all the engineering for you! The Zipper’s Muscle 103” Kit represents years of research and development. The result 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 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 heads and chambers, precision cylinder boring and honing with forged pistons, Red Shift Cams® performance cams and dual-piston cam chain tensioners, a ThunderMax® with AutoTune and MaxFlow air cleaner assembly.

All kits can be purchased whole or in any combination of desired components, please contact our sales department at 410-579-2828 for more details and pricing.

This kit uses your factory head and cylinder cores sent in for modification, expect 1-2 weeks completion time (during peak season allow for additional time). We keep exchange heads and cylinders in stock already modified for quicker turn-around; parts must be in nearly perfect cosmetic condition, expect the same from us. You can also purchase heads and cylinders outright (without supplying a core set). We will supply clean, reconditioned factory castings for your application – add part # 517-010 (cylinders) and 517-015 (heads) to your order.


Not legal for sale or use in California on any pollution controlled motor vehicle.
Not legal for sale or use on any EPA pollution controlled motor vehicle.

*To ensure you enjoy a premium experience, Please fill out a Build Sheet/Job Order Sheet prior to completing an order on the website.
Click here for Zipper’s Build Sheet/Job Order Sheet

Weight 1 lbs
Emissions Compliant

Country of Origin

Engine Type


Fuel / Air


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