i think the biggest problems with these carbs is the users lack of knowledge on how to tune them and possibly any other carb. it's rare that any aftermarket carb is a bolt on/no tuning success. these carbs may have some manufacturing issues but nothing that would prevent them from being good drivers. the 750's and 800's are stupid rich out of the box, but why should that be a problem not easy to overcome? they come with a manual explaining operation. do people read it or toss it? parts are readily available. i'm running two 600's on a ch28 and think they are more than a great pair. the factory avs's have emissions issues to overcome but once that's dealt with they are great drivers and performers.