IMO the PCIII was the way to go, but that's just me. They already have maps that you can download for your quad even though it's still got all the stock parts. (no need to learn how to "program anything)
Filter won't net you noticeable gains. My UNI cost me like $25 from Rocky Mountain ATV.
BTW if you take out the splash baffle out of the airbox all you get is a dirtier filter.
Yoshimura makes a damn fine exhaust, I almost bought that from Dave too. (Dave is the official clubb700xx officinado since he's now had 3 different brands not counting the Honda one it came with)
Remember a stock quad will benefit from a programmer no matter what (albeit small) since almost all stock quads come running lean from the factory.
I hope this helps....