I run premix on my QT50’s. I don’t have a lot of modifications. One is just the airbox removed. The reason I run premix is because of the improved 2-stroke oil today. It doesn’t need as much oil as back in the day. To much oil and it runs lean. For example, I have a 1985 Honda FL350 that says on the tank to mix 20:1, if I run that much oil I’m going to blow a piston and at $150 a piston, that gets expensive. I run between 35-40:1. Just my 2 cents.