Maybe the bigger question is, has anyone who HASN'T done a piston change (from OEM) had this happen? Which then leads to, why change to a lighter piston? Being an engineer, I appreciate the idea for reducing the reciprocating mass: quicker acceleration, less stress on attached members etc....For stuff like supermoto I get it. The littlest advantage can make a big difference. But I haven't been spanked by a modified BRP nor a stock one (stock meaning un-corked here) in the type of riding I do. Within the confines of the OEM covers on my bike, it's all stock. I've ridden with plenty of other BRP riders, and we all have our strengths and weaknesses. None of us have ever thought that the power of the bike held us back (suspension not withstanding....). The stock power plant leaves most mortals going "Holyyyyy Shittttttt" when they twist the throttle. The big differences seem to come in the tuning and rideability of the bike. If it doesn't work, no amount of power will save you. In my mind, it's the total package that matters. For my dual sport riding and occasional cross-country race, as well as the Kings of the West Rally, the stock internals of the motor work for me. They get me to the beginning AND the end of the event. About the only thing I'd consider changing from OEM is the intake valves for more longevity. But hey, that's just me.