Basically, OS and Nova have both figured out something in the carb department that just plain works better than everyone else. The only other carb I really like is the orange one that came with a Star made RB Xenon Alpha onroad motor. Basically it's a billet made clone of the Nova cast aluminum carb. I think some of the other Star (Sirio) based motors are coming with a non-anodized version of that carb now.