I have the HRC tip, otherwise a stock exhaust. Right now the average temperature is about 25, and i am at 1000 feet of elevation. I do ride a lot of open spaces, but also play in the valleys. I was running the 19E and had good pull from top to bottom, but when i backed off i felt i had far too much popping and banging, as if it were to lean from long wide open pulls. Also I had adjusted the mid range as rich as it could go with no affect on the popping and banging. My current hypothesis is that with the 21E needle I should be able to eliminate the popping and banging, then then slowly lean it out with the needle adjustment until i get slight popping and banging back on deceleration. If this needle proves too rich I may "tune" it by modifying my airbox, and/or my exhaust further. Also when running the stock carb, I found all the posted needle and jet settings to be far too lean. Never did get that carb to perform well, though I never tried to go much richer with it. Perhaps I have an extra healthy engine that likes it's air and fuel, or perhaps my fuel is different than what you guys run down there. Hmm. Thanks for filling us in with details. Keep us posted.