Waiting on these to come out which looks like next year but I don't know when ???. I had the 600 on it first which ran well but I couldn't get enough fuel through it no matter what I did and plug tips were always lean looking (very light grey to white) which never sat well with me but when I purchased the 650 avs it ran well out the box but needed a jet and needle change to richen it up slightly ,plugs are a grey to tan on the tips. Great street carb and very easy to work on. Doogie I have no experience with Holleys !