[ajh97blaster]

i wanna say 26 or 28 mm for the stock carb. a stock carb works well with just a exhaust but once you get ported cylinder and your head milled etc the carb is a little restrictive. im not going to mention anything about your exhaust because i don't have one so i can't offer any help. but alot of people will tell you that fmf's aren't the best pipes once you start doin serious mods! good luck!