This is it, horsepower junkies – The Big Gun!

Zipper’s engineering team developed the Muscle 124 and 128 Stage 4 kits for riders who want to win, every time. Careful testing of the latest technologies and components yields incredible power from the M8 platform on pump gas. Cylinder heads receive Zipper’s CNC porting to Stage IV specs for maximum flow using +2mm oversize stainless valves, and Zipper’s 4.250” bore cylinders are fitted with 12:1 thermal and friction coated pistons. Our Red Shift 588 cam optimizes the output of these powerful components; careful selection of intake, exhaust and tuning delivers impressive results to 6500 RPM. This is not a bolt-on kit. It requires strengthening of the engine base and drive line upgrades – not unexpected when you are almost doubling the factory output – and should be executed by an experienced professional. “Walk softly, but carry a Big Gun!”




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.
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