i am a lightweight too... around 145lbs and am quite happy with the stock suspenders. although the gold valves are always on my mind.
if your into touring/longer rides, like already mentioned, i would go for improved tourability. radar with a nice mount? heated grips(mandatory imho, and quite cheap if you get the insert type)? luggage solutions? just put on a 46l givi topbox, and i honestly don't know how i did it before!
exhaust will make your bike sound sweet. staintunes apparently aren't that loud, and have the option of installing a sound 'spud'. personally, i would not de-cat. i feel the performance gain vs environmental impact isn't worth it. hey, i ain't no treehugger, but i do what i can:)
pc? your results will vary. if it ain't broke, don't fix it. a k&n will make some sexy sounds and improve throttle response. and will nicely compliment an exhaust.
i am currently running w/o my pc, with exhaust and k&n, and it seems to ride just fine. although i am in winter riding mode, and things may change come summer when she gets ridden a little more aggressively. in the past i have had fueling probs, so go figure.
not sure how long you have been riding, but riding GEAR is always a very, very good investment.
p.s. just picked up a jr endurance honda riding jacket at neweunough... under 100bucks shipped. only sm and med, though!