hey what size jet did you put in your 400 because my dads has no power in mud he only has 25/10/12 all the way around it we was thinking about puting the stock 500 jet and neetle but i rather do something that i know will work and when dyno jet finaly makes a jet kit I will be to old to ride so brad or who ever did something to theirs please help me I have a k&n on it but it did not help much