I am going to install a dynojet kit, 4 into 1 Vance and hines(racing baffle)and k&n air filter, should I drill the extra hole in the carb slide or not? I want the most bang for my buck but want to eliminate the 3500 rpm flat spot.
If you already purchased the kit, you should follow their recommendations. Some kits require drilling an additional small whole in a specific location.
If not, and you just want the flat spot gone, why don't you just shim the jet needle with washers 1-2mm, raise the main jet size one-to-two sizes and synch the carbs? No drilling necessary and requires the same experimentation.
__________________ Most people would... "Um, I'm not most people." Okay, so we've traded bikes for a while [Damn, your bike's a POS! ], now give me mine back!! Ahh, what a sweet ride. Setup link(s): K&N, Supertrapp Aluminum Racing Series tunable slip-on exhaust, jetted, stock gearing & ignition. ZX-9R MPT max range ~266 - 275 miles & MPG tracker at Fuelly.com
the kit recommends drilling the extra hole for the slide but I have been told its not always a good idea, too much vacuum can make the engine hesitate right off idle if the slides move to quickly, I worry about having enough gas flow to keep up with the air filter and pipe given the ram air causing the flat spot.
time to pipe and jet the 96 ZX-11
], now give me mine back!! Ahh, what a sweet ride. 
