So I have my Mac muffler on with stock air intake

155 main with a 52.5 pilot runs good at 2 turns out, pulls strong

What do you think?
Rich?
Just right?

plug has about 300 miles on it with moderate driving

I seem to be getting about 39 mpg this way

run more miles and check the plug again.. mpg should be higher so maybe a little rich?
better rich than lean  

155 is overkill for sea level. If I was in Sag Harbor, Bridgehampton, Watermill etc where I have family I'd be running 152.5 or 150 over 52.5 or 50. You have the same problem on the island that we do here in Dixie, soggy air. Lean it out a stage or 2 on the top end, 1 down low, will run fine and bring your fuel economy up back a bit. Poorly atomized fuel (big jet) plus high humidity will coke up the cylinder head, exhaust ports, header pipe and muffler.

I ran a 155/55 jet set in the mountains and at sea level in WA. Bike smoked like an old tractor trailer and got a whopping 36mpg consistently. Pretty pathetic when that exact same bike with stock jets and modified exhaust in MS, TN, KY, AR, AL, FL and LA averaged 75mpg commuting and a high of 85mpg on the freeway...

main jet replaced to a 152.5, I'll stick with the 52.5 pilot for now, I know Im never done tinkering with this thing  

https://www.youtube.com/watch?v=qpHQk-pA6fI