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Performance Upgrades



There are four stages of Screamin’ Eagle® performance upgrades. We are here to help you make the decision that best fits your motorcycle performance needs.

Extensive research and development goes into every Screamin Eagle® performance product prior to production. They are engineered and tested to meet Harley-Davidson® standards for quality, performance, durability and dependability. They are also street performance compliant and retain motorcycle factory warranty. 

Moving more air through your engine = more horsepower and torque. Pretty damn simple. A Stage I upgrade includes high-flow air cleaners, exhaust mufflers and the proper electronic control module (ECM) tuning, using the Pro Street Tuner. Stage I is required for other Stage upgrades, and tuning is required for each Stage upgrade. This upgrade can be installed without engine disassembly. ECM tuning required.

This is how you can make your engine, your engine. Performance when you want it. Your ideal idling sound. Your everything. By updating the cam and valve train, you control the timing of all major engine events. Every cam has unique characteristics so your engine can be tuned to focus on how you want the performance to feel.

TORQUE KIT: Crisp throttle response and acceleration you can feel at lower RPMs.

POWER KIT: Adrenaline-pumping acceleration for those who like to downshift and ride in the higher RPMs. Stage II upgrades can be added on to your Stage I upgrade by simply selecting the cam kit that best fits your riding style. The upgrade requires minor engine disassembly to replace the cam. Adjustable pushrods allow for cam installation without removing the rocker box. ECM tuning required.

There’s no replacement for displacement, and that means more cubic inches. Stage III upgrades add size to your engine and increases compression for a bigger bang. With the proper cam profile and free-flowing intake and exhaust, a big-bore motor can be tuned to deliver the power to ride any way you like or the power to ride two up, and feel like you’re solo.

Upgrade requires removing the engine’s top end and swapping the cam. The engine remains in the chassis and no machining or custom fitting is required.
Special tools and ECM tuning are required.

Now that you’ve got the volume, use it the right way. By adding high-flowing ported and matched upper-end components to the bigger engine you can make sure you’re moving as much air and fuel as the engine can take. This stage adds more horsepower to the already impressive Stage III upgrade.

Maximize your horsepower – not the labour. Similar to Stage III, upgrade requires removing the engine’s top end and swapping the cam. The engine remains in the chassis and no machining or custom fitting is required. Special tools and ECM tuning are required.

If the Stage IV is still not enough performance, the all-new Stage V Tyre Shredder Kit adds an engine displacement increase to 110 cubic inches without requiring additional engine disassembly over and above the Stage IV upgrade. This equates to a 38% increase in HP and an 18% increase in torque that carries on through the RPM range.


Now time for some inspiration. We have a catalogue of YouTube videos available on our channel which we would recommend you have a look at to get your creative juices flowing! For now, we have a few listed here.


To discuss the options for your bike pop in or call us on 0141 883 1450. Or get in touch with our Custom Specialist, Darren, by filling in the form below.

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