Free Shipping on Purchases Over $150 to the United States!

Honda Grom Stage 3 | DHM Piston, ECU Reflash, and TB Camshaft

ECU Core

The DH Motoring Stage 3 Package includes the following:

  • DHM ECU Flash
  • DHM High Compression Stock Bore Piston
  • TB Camshaft
  • NGK CR9E Spark plug with spacer

Combined with your aftermarket intake and exhaust, this is the most you can get out of your Grom without doing any head work. After dyno testing we were repeatedly seeing 13.5hp at the wheels (SAE) run after run! The Stage 3 package makes more power than a stock Grom at every RPM and double the horsepower at 9000+ rpm! 91 octane fuel is absolutely required. Any fuel with a lower octane rating may result in engine damage!

You can choose to receive a preflashed ECU instead of sending yours in ($95 extra), or you can send yours in to be flashed. 

An oil cooler and extra crankcase vents are recommended for this kit. 

We offer the following crankcase vent systems:

AvailMS Crankcase Vent 

MO Power Crankcase Cover


Customer Reviews

Based on 67 reviews
Christopher Tripp
Stage 3 kit

Super happy with the DHM stage 3 kit for my 2019 monkey. Huge improvement in power and torque. Runs amazing with 100 octane

Dwight Kovich
Great product

Wasn’t to bad to install took me about a day to throw everything together and it feels like a complete different bike. I absolutely love this kit and hope to treats me well down the road.

Kane Statham
Easy and well supported

The kit went in easily.
Even the ring gaps were right out of the box.
I had a few questions and they were answered kindly even though they were pretty basic.


Easy install. Allot faster

Jacob Villoch
Stage 3 kit

Everything about this company is amazing. They reply to emails so fast to any questions. Very fast shipping. If you follow instructions the stage 3 kit is easy and good upgrade.