are you going w/ a different exhaust and/or air intake?  What altitude do you live at?  Need answers to give you an answer!

If your staying with the stock pipe, pull the brass plug over the mixture and set it to 1 3/4 turns out from soft closed, a 147.5 main (with a 150 at the ready), and 1/2 the spacer is where I'd start.

btw it's more the elevation to worry about than the climate