well thing is u dont have to start messing with ur jetting until like 500ft - 600ft from sea level but in all honesty it be better to run richer than leaner but i would go with 310 main and try that run it see how it runs and check the plugs now i reccomend that u do a high rpm shut down on it to see what tha plugs look like and WOT u kno jus to be on tha safe side |