Dry Spot @ 3500~4000

[CaliCafeSeca]

So, I'm not the engine master, but my thoroughly trained, moderately experienced ('bout 5 years) friend and I couldn't work this out.....

I have the Factory Pro Ti Jet Kit and Vance and Hines that I installed about 2 years ago, so I'm not too certain exactly what we ended up with, though I do remember being able to pull the carbs and change the innards in about 20 minutes I did it so many times. After we got it all to the best "road test" condition, impeccable balance, the bike is snappier than ever before.....but....

She still runs just a touch lean, as evidenced by nearly rare, always mild popping on slowing under load. It's really mild, barely occurs so enjoying the amazing throttle response I settled.

There's this one thing though, when coming out of corners or any slow down and get back on, the low end reacts great, then at around 3500 rpm, it goes fluffy on me after the fluffy spot it bursts to life again, and I can't for the life of me adjust it out. I live at ~3000ft and the problem decreases a little at higher altitudes, so I'm assuming it's a dry spot. What do you guys think is the best approach?