I have a 400ex and would like to put some mods on it. What would be the best for rideing on trails. Would it be bad to bore it without exahust. How much would a bore kit and exahust cost. Any help is apreciated.
Thanks

 

I wouldnt worry too much about a bore kit. IMO the exhaust would be the best investment a person can make. Not only will it make a noticeable difference on the performance but it makes your quad sound 10x better. Exhausts can range from a couple hundred to six hundred or so I believe I have seen them priced at.

 

for trails just get the pipe. keep the engine reliable and predictable for now, at least thats my opinion.