ARB E.O. #'s D-644, K-001, K-001-1, K-001-2. K-001-3ThunderMax® 50 is the most powerful, cost effective, EPA-compliant tuning device in the industry! ThunderMax® 50 provides excellent performance while meeting the tough emissions standards of California Air Resources Board. With its intelligent design, ThunderMax® 50 is continually tuning the engine, adjusting all points of the base map to meet the Air/Fuel targets. Wide-Band sensors provide feedback to the ThunderMax® AutoTune module for automatic AFR adjustments. This proven system provides excellent performance under any riding conditions. ThunderMax® 50 is the one that WORKS!
ThunderMax® is an industry award winning, performance ECM designed specifically for EFI equipped Harley Davidson® motorcycles. This highly advanced, stand-alone tuning system utilizes proprietary AutoTune technology specificly designed to interface with wide-band oxygen sensors to automaticly adjust a wide range throttle positions and RPM ranges to deliver unmatched performance and driveability like no other product in the industry. ThunderMax® is made in the USA and comes 100% assembled, ready to install with no wire-cutting or splicing required. Simply replace the factory ECM and oxygen sensors, load a map, and enjoy your new ride!
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.
We’ve taken the hassle of converting your late model belt driven H-D® to chain drive. Whether you’re interested in a different final drive ratio, added driveline strength or more clearance for a wider tire, these kits will make your life easier. Kits are available with durable, high wearing RK Pro O-Ring chains (best for street use) or RK's brutally strong, non-o-ring DR (Drag Race) chain.
*** Due to supply problems, 1985 - 1999 and 2006 and later kits are only available with chrome steel or silver steel rear sprockets!!! The largest rear sprocket available is a 51 tooth***. 2000-2005 kits are only available with chrome steel or black steel rear sprockets.
*To purchase item(s) below select the radio button next to item of your choice, then click add to cart*.
D&D has expanded its popular Bob Cat 2-into-1 exhaust systems to include Dyna® models, along with the original Sportster® and XR1200® pipes.
All Exhaust Systems listed on these pages are designed solely for Competition Race Use Only.
Not designed or legal for use on a public highway.
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.
The D&D Fat Cat 2-into-1 exhaust system is an excellent choice for engines with performance modifications from stock to plus-25% displacement, delivering a torque curve that is high and wide, with a strong top-end pull. Excellent workmanship inside and out; broad power design really shows up on the dyno.
All Exhaust Systems listed on these pages are designed solely for Competition Race Use Only.
Not designed or legal for use on a public highway.
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.
A nice power increase that’s easy to install! Zipper's Premium MaxFlow Air Cleaner Kits
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.
Please choose your application below then select the radio button next to the item to purchase, then add to cart
A nice power increase that’s easy to install! Zipper's Premium MaxFlow Air Cleaner Kits
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.
Please choose your application below then select the radio button next to the item to purchase, then add to cart
Is your bike already equipped with a factory Stage I performance air cleaner? Zipper's MaxFlow Stage I Upgrade Kit takes about 5 minutes to install - the difference is immediately noticeable!
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.
S&S air cleaners for EFI--add the famous classic teardrop air cleaner assembly to your ride. Replacement back plates, covers and filter elements for S&S applications available separately for repairs or maintenance.
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.
Please choose your application below then select the radio button next to the item to purchase, then add to cart
Zipper’s Popular Muscle 107” Kit for Twin Cam® 96/103” engines boost torque and horsepower north of 120! The Muscle 107 is a top end and cam kit that gets its displacement boost by increasing the cylinder bore size to 3.937”, while retaining the factory 4-3/8” stroke. Your cylinder tops are decked for trueness and new 10.6:1 forged pistons are precision-fit using the latest Sunnen equipment, while your heads receive Zipper's high-breathing Stage III treatment with CNC porting, new guides, oversize valves and performance springs. Our Red Shift 577 cams are perfectly matched with the heads and piston to provide big torque & HP across the entire RPM range. Red Shift Dual-Piston cam tensioners are included with Pro-Taper pushrods for a stable valve train and EZ-Adjust covers, with all gaskets needed for assembly. Highly recommended option: our 417-498 blueprinted cam chest/oil system upgrade for improved oil delivery, increasing reliability and durability.
This kit is for the aggressive rider that likes to regularly twist the wick and run up front!This kit uses your factory head and cylinder cores sent in for modification. An exchange may be possible once your cores are cleaned, inspected and qualified for exchange.
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.
Zipper’s Muscle 117” Kit for Twin Cam® 96/103” engines increases displacement with new 4-1/8” bore cylinders while retaining the factory 4-3/8” stroke. New cylinders are stress-relived before being fitted with 10.6:1 forged pistons using the latest Sunnen equipment, while your heads receive Zipper's high-breathing Stage III treatment with CNC porting, new guides, oversize valves and performance springs. Our Red Shift 577 cams are perfectly matched with the heads and piston to provide big torque & HP across the entire RPM range. Red Shift Dual-Piston cam tensioners are included with Pro-Taper pushrods for a stable valve train and EZ-Adjust covers, with all the gaskets needed for assembly. Case boring required for 4-1/8” cylinders, Timken® bearing conversion and cam chest/oil system upgrade recommended. Amazing increase in Power and Torque!This Kit uses your factory head cores sent in for modification. An exchange may be possible once your cores are cleaned, inspected and qualified for exchange.
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.