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

ECU Core

The DH Motoring Stage 3 Package includes the following:

  • DHM ECU Flash
  • DHM High Compression Stock Bore Piston
  • TB Camshaft or Decha HR 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 68 reviews
Would not recommend this kit

Got this kit hoping to gain power, lost most power. Followed the instructions and it seems to have less power than stock. Can only get to 55mph before the bike bogs out. Having to rev the crap out of the bike to get anything. No solution for my problem. Would not recommend at all. Save money and buy a tuner.

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