This kit in fact does NOT include all required parts to help your carb perform its best.... at least not for an 07 400EX. Yes it has a variety of main jets, a new needle and misc. hardware but it does not have any pilot jets which are needed if you install an aftermarket exhaust system (header/muffler or just muffler) on your ATV. The kit fit great but the pictures in the instructions and the instructions themselves could be much better. If you have never rejetted a carb before and want to use this kit, make sure you have someone with you who knows what they are doing and that your local shop is open. I'd actually look for a more "complete" kit though.