I have a suzuki z-400 with an alba slip-on pipe. I have a K&N airfilter with outerwear and i am running my z with no airbox lid. I also rejetted my carberator to a 155 main jet and I am pretty sure to a 25 pilot jet, I am not positive about the pilot jet. When I would take it to big dunes like dumont it just couldn't pull comp. in third. To get to third I switched to 13 tooth sprocket in the front and a 41 tooth sprocket in th back. I figured this would slow my third down, but it would still be faster then my old second and I would be able to climb in third. Well when i took it to the dunes it still couldn't climb in third. It sounds like it is hitting the rev limiter when I go at a hill, and it backfires sometimes when I let off on the gas. My Dad's z is the same as mine except that it has a full youshimura off-road exhaust and the main jet is a 150. He switched his sprockets before me and it made a big difference for him. When I get off mine and on his it is a night and day difference. I can climb in third up almost any hill at dumont on his and only on the really steep long ones do I have to down shift to second. I was wondering if anyone could help me figure out how to get mine to run better. I dont know what mod to make to it to get more power out of it. I know that not all quads are the same stock and that my Dad's might just run better, but it run's a lot better and I think mine might not be running right. Any help will be greatly appreciated and If you need more info to help just let me know and I will help you.