Can anyone tell me the advantage of a K&N air filter, verse stock.

 

None...it will suck fine dirt into your enigne and toast your valves!

 

Is there any other way to increase performance?

 

There is all sorts of stuff on the market from big bore kits, to cams, high compression pistons, exhaust, and jet kits...

Personally, you might wake it up some with jets and exhaust and better flowing exhaust, but I don't know if it is worth it to go too crazy with internal mods...

 

the older rincons are fun ones to play with there is so much you can do to them. a lot of guys i know are running uni filters.
you can pm me if you want to get leads on the other stuff you can do.