You're talking about the float bowl mod where you vent it back up into the airbox so it gets fresh air? - eliminating the factory valve (If not, post a link to share). I've done this - if you haven't do it.
Are you running a stock air filter? If you also read in Ken's article, he states the main jets from the factory are huge, due to Kawi's design. If you are using an aftermarket filter, you'll want to drop the mains down to the 150-160 range. Provides much better throttle response, and better overall deliverable power (at least in my results).
I'd check out Web ZXR
Tech Tips - 93-03 Models
section & read about the mods I'm referring to.