Performance Kits

Bolt-on performance kit with bolt-in cams and premium tappets. Easy installation with no machining or rebalancing. Uses stock heads, pushrods, and fuel system.

Complete bolt-on big-bore kit that raises displacement without case machining. Includes cylinders, forged pistons, upgraded oil pump/cam plate, valvetrain hardware, and all gaskets and bearings for installation.

• Bolt-on power: +40–50% on stock 107", 114" and 117" M‑Eight motors.
• Compressor and turbine housing with Garrett internals; plenum with integrated blow-off valve.
• Includes injectors, spark plugs, boost gauge with mount, oil feed/drain lines, custom cam cover, tune files, hardware and gaskets.
• Requires Thundermax ECM (sold separately). Does not fit Twin Cooled or non-removable fairing lowers. Offroad use only.
• Made in the USA.

Complete kit to convert 114" or 117" oil-cooled M8 engines to 132" displacement while retaining stock height and serial numbers. Includes adjustable pressure relief valve, S&S valve springs, big-bore cylinders, MLS head gaskets and a performance-matched 550 cam.

132" high-compression kit fits 114"/117" motors with 4-1/2" stroke flywheels; 136" requires a 4-5/8" S&S flywheel (sold separately).

132" high-compression kit fits 114"/117" motors with a 4-1/2" stroke flywheel only. 136" big-bore requires an S&S 4-5/8" stroke flywheel (sold separately).

High-compression kit enabling 132" or 136" big bore capability; requires specific stroke flywheels. S&S flywheel needed for 136" (sold separately).

Fits 114"/117" motors with 4-1/2" stroke flywheels; 136" build requires S&S 4-5/8" flywheel (sold separately).

• Converts stock engines to 124" for non-balanced Twin Cam models.
• Complete kit with S&S heads, pistons, cams, tappets, pushrods, rocker arms, hardware and gaskets.
• Made in the USA; EFI recalibration required. Fuel or ignition system not included.
• Verify all clearances and assembly specifications before installation.

Comprehensive kit to upgrade a stock Shovelhead; includes cylinders, pistons, flywheel assembly, rods, pushrods, gaskets and a heavy-duty top motor mount.