I was wondering if anyone knows if there's a bigger carberater for the 400ex where can i get one and who makes it?Also if i bought an after market rev limiter would it make a big difference on my 400ex?

 

A Rev limiter will void your warranty. Unless you live in a area where you can really open up all of that 400 I would not worry about a rev limiter. The same goes for the larger carb. You should also try to use the same company to hop up your quads performance. Each company perform tests to get maximum performance. For instance the cam they install might give the quad great bottom end but sacrafice the top end so what they do is design a pipe to make up for the lost top end.