Nicks a nice guy, but I'm telling you straight up if you run a full system such as the muzzy or D&D you need to changes the mains to make it run right, selecting the correct main jets is the first step in the tunning process and the pilots have little or nothing to do with 6000 to 8000 rpm range unless your cruising at 1/8 throttle or less and have a surging problem so adjusting them to cure a flat spot at 8000 is ridiculous, use the tuning guide, good information written by professionals. I've been building and modding and racing bikes since the early 80s I've had allot of bikes and most of them are big bikes, I know that the EX500 is a beginners bike and I think thats where the problem with this web site stems from, you don't have allot of people buying these bikes to hot rod or race and even the some what experienced guys are afraid to touch the carbs. You heard all the horror stories about flat spots, well don't change your mains with that muzzy pipe and you to will have an unhappy story to tell! I don't mean to insult anyone, and you can believe what ever you like. Just follow the jet kit instructions as I told you and don't be scared to pull the carbs they are not some magical device that you'll screw up by touching them as many seem to believe, just keep them clean and again follow the instructions, none of these people know more about jetting than Factory Pro or Dynojet. And don't believe all the BS on here it comes from inexperience or experience with people who don't know what the hell they are doing. I want to leave you with this, with what I've done to this 89 EX it will power wheelie in first gear at about 4500 RPMs and I don't mean with clutch I mean twist the grip and it comes up to the pivot point and will flip if you not careful, and the gearing is only a 16 and 45 (2.81 to 1), not the 15 and 44 (2.93 to 1) that others are running how many stock air boxed, slip-on piped EXs will do that, speak up if yours will. Maybe I'm crazy but the bikes I ride/race make hp in the 160s not 50s, so you believe who ever you want, but follow the god damed instructions that came with your jet kit!