DAD, I'm currently running 45mm on my 600R, modular, bought off ebay back in either 04 or 05, with 2 pumps, all the bypasses, and a Kinser filter for $325.00, works great, not hard to tune at all, not all that particular to weather conditions, I usually run one pill, in the Spring, then in the heat of the summer, one different one, then in the fall, back to the spring one. I use a Kinsler Hi-speed, and don't use an "s", or idle bypass, just richen or lean the low end, off the barrel valve, don't get any easier than that! Bob