Best Milwaukee-Eight Performance Upgrades

By Brett Foote - October 30, 2017

As our forum members point out, not all Milwaukee-Eight Stage kits are created equal.

Regardless of your opinion on the highly controversial styling of the 2018 Harley-Davidson lineup, we can pretty much all agree on one thing. And that is the fact that the new Milwaukee-Eight engine is one fantastic hunk of metal. Compared to the outgoing Twin Cams, the M8 produces more power and faster acceleration. And it does so with less parts and an adjustment-free valve train while producing less heat and mechanical noise. Oh, and with better ergonomics. What more could you ask for?

Well, for starters, more power. After all, you can never truly have enough, can you? And Harley makes it easy by offering upgrades you can have installed before you even leave the dealership. Their Stage I, II, and III kits are designed to add power, torque, and throttle response without sacrificing reliability or ride quality. So the only real question left to ask is, which one(s) are worth the money?

If you want the answer to that question, there’s no better place to turn than the Harley-Davidson Forums. After all, plenty of our members have already installed these performance kits on their Milwaukee-Eight bikes. And they’ve racked up plenty of miles on them. So that’s exactly where JHC210 decided to head for some advice.

“Looking to wake up a ’17 Limited Low. Is a Stage I from the dealer worth it, or should I go directly to a Stage II or up? If I am going to spend the coin, I only want to do it once.”

Interestingly enough, members present some mixed opinions on the matter. For todd-67, buying and installing the Stage I bits himself seems like a better way to go.

“Stage I being mufflers, air cleaner and tuner from the dealer, no it’s not worth it. Do it yourself with your mufflers of choice. Get a K&N and install the tuner yourself. Stage I in the M8 is not the boost you got with a Stage I in the Twin Cams. Sound is a little better, throttle response is about all you will notice. The Stage II brings on a different set of circumstances because of the warranty. If you are thinking of going that route, then yes, do it within the 60 day window and get it on the warranty.”

Others, including dwagar, feel like the Stage I kit is still worth the money for what you get in return in regards to the Milwaukee-Eight.

“I thought it was worth it. I installed the stuff myself and saved the cost of labor. If you’re doing your own install, you have to also buy the cable to flash the tuner. Bonus is you can now do a couple of auto tune runs, which I think is worthwhile.”

For some, like Cbyway, the answer isn’t so black and white.

“I think it depends on the definition of worth to the person doing the upgrade. Had the Stage I completed before I took delivery of the bike. I didn’t just add the slip-on mufflers, I did the entire SE Street Cannon Exhaust system along with the intake and tuner. Can tell a difference vs. my brother’s stock 107, but I also think my bikes and truck run better when they are clean and waxed. I know it sounds better and was worth every penny to me. To others it was a waste of money. Don’t sweat what others think.”

Regardless, times have certainly changed. It doesn’t seem like you’ll get quite the same effect with the new Milwaukee-Eight upgrades, thanks to changing emissions standards.

“It is not as good a bang for the buck as it used to be,” says martin10. “You get approximately half the gain for twice the price as in the past. So if money figures into being worth it, I am inclined to say no.”

“The days of upgrading your Harleys like we used to are over,” adds PDB17UltraRG. “Used to be pretty easy to do, getting much more out of them. The new EPA regulations have messed all that up. This new M8 motor was designed with the new regs in mind, so you’ll never get the sound or the power we used to get. All the bikes with the Stage updates have a lot of issues after the upgrades. Not worth the headaches or the loss of warranty, at least for me.”

On the other hand, the Milwaukee-Eight is pretty excellent in stock form, which may negate the need for these upgrades altogether. Which also might explain why folks aren’t seeing the gains they used to see with the Twin Cams.

“Go Stage II with a cam and you’ll see some nice gains,” says jgos929. “I did slip-ons only and couldn’t be happier. The M8 is so good out of the box.”

“That is what I’ve said all along as well. The M8 runs so well as it is, the Stage I just doesn’t make hardly any difference over stock,” adds lyork.

So it would seem that the OP would be better served sourcing his own aftermarket exhaust upgrade. Or just springing the extra cash for a Stage II kit. But what we want to know is, what do you think of these new Milwaukee-Eight performance upgrades? Head over here and chime in with your thoughts and personal experiences with Harley’s latest and greatest powerplant!