As far a jetting, you'll have to read the color on your plugs or the top of the pistons to see if you can jet down. I don't think anyone will say "yeah, you can" when they don't know what your plugs look like. What elevation do you ride, and what "average" temperature? These are the main factors. 156.3 is the factory main jets.
If you do an air mod, it will lean you out some also. You will have to keep a close eye on your plugs. The Flow-rites in my dash are from SLP (Starting Line Products). An adjustable air vent would be sweet, because you could change your jetting slightly simply by opening/closing them.
I have SLP triple pipes and flow-rites. SLP was able to provide me with a base line jetting chart. Of all things, the stock jets are what I am running. I did the pipes first, and was running pretty rich. I thought I was going to have to jet down. I decided to add the flow-rites first, and it leaned it out quite a bit more than I expected. Temperature makes quite a bit of difference, it is usually around 20*F here. Last year on one of my rides it was about 0*F, and my plugs were as light brown as I would ever want to see them. What I'm trying to say is I like to jet a hair rich so that I don't have to freak out when it is a little colder than normal.
Jetting can be a PIA to get right, you have to be patient and plan on sacrificing some riding time.
