Thanks Lancer, here is what I have so far...fairly open pipe but it does have some resonator/baffle to create some back pressure, K&N drop in air filter.
I first replaced the stock spacer with a #4 nylon spacer from ACE, that eliminated the midrange surging I was getting when I first bought the bike.
Rode that way for a few months but didn't feel like I had any power on the upper throttle range (which I don't use much!) so I put in a 150 main from Lancer's kit....worked as expected (good!) although I was getting some serious POP on shut down.
Installed the 52.5 w/ bleed holes from Lancer. That seemed to help with some of the low end sputtering I was getting in cooler weather (although I really think that is the vac petcock which I'm replacing with a Raptor arriving tomorrow) and seems to have eliminated the POP on shut down. I also now have the air screw out only 2 turns which is good.
I sometimes get some afterfire when really winding it out between gears but really nothing to write home about.
I just took everyone's advice and went slow to see how the bike would react. So far it's been fun.
I think I'm very happy now!!!!