I'd bet Polaris is expecting the 146 to see more trail riding and high speeds, and didn't want to take a chance on a lightweight track. Given the issues people are having with the series 8, I doubt it'd last long at all max blasting down the trails. I also don't think there's anything available in 144/146 that's lighter than the 155 series 8, unfortunately. You could put the shorter cooler in the 146 sled, but the would be expensive and take a lot of effort. That said, the 146 Slash sounds like a lot of fun, and if you could make one <400lb, it'd be all the better!