I don't want to change the exhaust as I don't want the bike any louder. Will there be much improvement in real power ( will I really notice it) if i fit a K&N type filter, fit extra filtered breathing holes into the airbox and re jet?

 

What's the point in jetting your quad, putting a performance filter on and customing the airbox if your not getting an aftermarket exhaust. You wont really see any performance upgrade but your quad will have better throttle response and also breath a little better with the filter but no major power gain like if you were to put a pipe on. You dont have to get a loud pipe there a many exhaust system for the z250 that are not all that loud. I would look into a pipe, jets,and airfilter if you want to see any performance increase. They dont make to much motor mods for ther z250 so those are really your only opptions.

 

Thats settled it then.....leave it standard!