Dang,
I'm south of you about 50 miles, so basically the same elevation & climate
I've got mine setup with a cone filter and a Fishtail exhaust that doesn't have much baffle.
Stock is Main Jet 145, Pilot Jet 52.5
I also had trouble hearing much for differences but felt I needed to feed it a little more, so I upped my Main to a 147.5 and the Pilot to a 55. I haven't taken the top of the carb off to fiddle with the white spacer, but I feel mine runs strong and pulls hard everywhere I want it too, so I don't see much reason to tear into that yet.
I think that my backfire pops are mostly related to possible exhaust leaks that I need to better address. When I shut mine down, I usually only get a small poof, so I believe it is jetted about right
Best of luck getting it setup, maybe our paths will cross, or we will be able to ride together sometime.