what would be the best exhaust for the 250sx.
i do a lot of trail riding.

 

The stock exhaust would be best. The only aftermarket system currently available, that I am aware of at least, is the cobra. They only offer the cheapest, lowest quality material pipe they make for the SX. The headpipe and silencer run about $90-100 I'd buy one only to replace the factory if I had to. The cobra also doesn't have a spark arrestor if that is a concern for your area.