If the bike is set for ULG then running avgas will probably lose you power, unless you modify the motor, and jet correctly to take advantage of the characteristics.
Steve's F3 is making over 70 gee gees on ULG so it ain't that bad.
100LL avgas would need higher compression than ULG, more ignition advance and leaner jetting. If you just pour it in without changing anything you'll run rich and the fuel can't burn properly or completely.
Many people think that just throwing in the best fuel available is the way to make power, and this theory may work on an engine that can adjust all it's parameters to suit with fancy ignition systems and clever ECU's, but unfortunately the NSR is only as clever as the guy twirling the tools.
One good thing about 100LL is that it's quite forgiving on the jetting. ULG will make power right up to a point, and then start to detonate. Avgas will lose power at the point of no return, but doesn't tend to detonate unless you get silly with the jetting.
So you want some advice I suppose? Well, if the rules say you can run avgas then use it and reset the motor to suit. You get more power and it smells great
It just costs you more 
As for the jet kit, chances are that it's a ULG kit, so it'll work better on the ULG than 100LL. The major difference is in the needles. The ULG needles are richer than the 100LL needles. However, I've used the ULG kit successfully with 100LL. The best thing with the kit is the adjustable needles. They are certainly not a gimmick.