Hi Julian, Yes, Stuart at Premier managed the repair of my car when I had my 'incident' at Coventry earlier this year and offered me an upgrade of the flywheel while the engine was out. It has made a big difference in terms of throttle responsiveness and precision. Although I have yet to properly explore it on a track, there are (positive) implications in terms of cornering and the engine feels a lot more responsive and 'sporty' after the upgrade. The lighter flywheel needs a different clutch which is sharper and has a shorter travel, making ot more precise, facilitating quicker gear shifts. It also means that it's less comfortable in traffic/city driving which is a downside. I had the original clutch servo which made it very heavy, but that has been improved by fitting a smaller clutch servo (approx £80). I believe that Stuart is now using the smaller servo as standard but you may want to check with him. Whether I'd recommend it or not depends on what you primarily want to use the car for. If you are competing or primarily using your Caterham for track days and care about performance, then yes, it's worth it. However, if your car is mainly for road use, then you may not find the changes to your liking nor the upgrade good value for money (Premier Power is all about performance after all). I'm happy I did it though, if that means anything. Hope that's helpful. Best, Charlie