Who has performance parts for honda fourtrax 90? like a pipe or muffler,or any other things I can do to keep my kid on it for atleast another year?

I thought about the same thing, and I found that DG makes a pipe for it--cost is $120 thru Rocky Mountain ATV. Don't know if it does much for power though... As far as other engine stuff or better shocks, I haven't found anything.