I live in Pensacola Florida so I am definitely at sea level with mucho humidity. I have an 06 450 LE . I have run 4-5 tanks of gas and it seems to run just fine. The only time I have questioned the jetting was on a cold 50 degree morning when it would pop on deceleration until it was completely warmed up. I have a ziptie fuel screw on order but how do i know when it is adjusted just right?It sound like many 450 owners go to a 170/ 48 combo. how do you know that is correct?