There’s nothing subtle about a Harley-Davidson® touring bike, especially a Milwaukee-Eight. And there’s nothing subtle about the ear-to-ear grin you can’t control every time you fire it up. That’s what Harleys are supposed to do. Of course, once you ride the “new” off it, it’s time to start figuring out how to up the torque, the horsepower and the classic Harley sound. It’s what you do – even to an already great engine platform.

There’s a lot of talk among touring bike owners about starting your upgrade at Stage I … if it’s worth the expense, if it really improves performance, and if your bike really needs to be modded so soon. Well, the answer depends on whether you really want a better running ride than you brought home. And yes, starting at Stage I upgrades is a must. Stage I is the performance foundation necessary before even thinking about Stage II upgrades and beyond. 

Harley-Davidson Stage 1 Performance Upgrades at Fat Head Cycles

Our best picks for a Stage 1 upgrade bundle for your Milwaukee-Eight Harley-Davidson include the following motorcycle performance parts, all of which can be purchased on our website in our Chrome Package or Black Package:


D&D has designed an impressive new exhaust system for your 2017-2019 Harley Milwaukee-Eight motorcycle.  It’s specifically engineered to pump up the bike’s horsepower and low-end torque. This good-looking pipe system delivers a deep, throaty sound to your motorcycle, even at idle. Check out some of the additional features:

D&D Billet Cat Exhaust Black

D&D Billet Cat Exhaust Chrome

  • The M8 Billet Cat full system is equipped with exhaust gaskets, heat shields, a baffle, brackets and a bolt kit. It includes 18mm oxygen sensor bungs and a 12mm insert for the 12mm sensors.
  • The system features a 2 1/2” core Vortex-wrapped baffle that delivers an impressive increase in performance on 107-inch to 124-inch motors.
  • The 4” muffler body is connected to a double-stepped header that graduates from 1 3/4" at the head, up to 1 7/8" to 2 1/8" at the collector. The final measurement graduates to 2 1/2" at the point where the header connects to the 4” muffler housing.
  • D&D now gives riders the option of choosing their end cap type. It provides riders the ability to swap end cap styles while maintaining the same exhaust system. 
  • Choose an optional Ghost Pipe if you're interested in balancing out your look. 


The BIG SUCKER™ air cleaner Stage 1 kit is designed to fit all 2017 – 2019 Milwaukee Eight touring motorcycles. New technological developments resulted in new, patent-pending system design for a hidden breather backing plate. Each breather now includes O-rings at the heads and proprietary breather tubes that significantly increase airflow – and more air equals more power. The new system also takes care of a few common problems:

  • It recycles excess breather oil back into the bike’s engine, eliminating common oil issues eliminates oil-based issues commonly linked to M8 engines. This action prevents oil from saturating the oil filter and limiting airflow.
  • A newly redesigned oil catch-can is built in to the backing plate.
  • The filter top plate is constructed of aluminum and includes integrated mounting studs and directional air cleaner for better performance and an increased lifespan.
  • The washable and re-usable performance filter is made of red, pre-oiled, surgical-grade cotton.
  • This filter is enormous! It has more than 200% more surface area stock filters. The tapered shape provides an increased surface area that outmatches any other comparable performance intake option on the market.
  • The backing plates are available in two styles: chrome or black finish
  • Each M8 Big Sucker Stage I kit includes a one-piece backing plate, one performance filter and top, breather tubes, one oil catch-can (built in to backing plate), hardware and gaskets.


The ThunderMax® system puts total control over your EFI back into your hands. It’s a stand-alone tuning system designed with proprietary Wave Tune AutoTune technology. It perfectly interfaces with your new wide-band O2 sensors that come with this ThunderMax tuner. While you’re riding, it automatically analyzes and adapts to an extensive range of throttle and RPM changes and positions. These automatic adjustments seriously increase your Harley’s performance. This award-winning system is manufactured in the United States and ready to install – no wire splicing or cutting required.

In addition to the ThunderMax® ECM, two wide-band oxygen sensors and a tuning cable are included in the kit. The tuning suite software allows you to monitor and/or adjust the following, including diagnostic codes, warm-up settings, ignition timing  and more:

  • Engine temperature and alarm
  • Accelerator pump simulation
  • Fuel injection pulse
  • Idling speed and revolutions limit
  • Deceleration pop control
  • Speedometer calibration
  • Real-time engine tuning
  • Running statistics and logs

Your new ThunderMax tuner will adapt seamlessly with any future upgrades (Stage II, III and beyond) to your motorcycle, never being outgrown, and also never needs to be dyno-tuned. Your ThunderMax module is backed by a 3-year manufacturer warranty and unlimited manufacturer tech support. 

Let’s face it … there’s a noticeable difference to starting with a stock bike and climbing onto a Stage I M8. Using the right motorcycle performance parts means a significant improvement in drivability, breathing, throttle response off the line, efficiency and sound. Stage I is just the beginning. Throwing more fuel and air at the cylinders is the most affordable way to bump up performance.

We will be offering two Stage I Performance bundle options on our site - The Chrome Package and The Black Package

If you’re interested in purchasing one of our Milwaukee-Eight Stage I Performance Upgrade bundles, simply visit our Chrome or Black Package product pages to learn more and purchase. Shipping is free to your door in the United States. 

If you're looking to have your Stage I upgrades installed in our shop in Thurmont, MD, simply complete the form below or give us a call in the shop, 301.825.9007.