As far as spending $400.00 more for 32mm VMs I would get rid of the stock airbox and use a set of K&N pods at 100.00 for the set. The bike will breath a lot better, have better than stock low and mid rpm throttle response, with a better top end. Also you said you had the fuel right and it was lazy in the middle. Where were you setting the fuel 14.7 to1? Fuel number don't have to be at stoich (14.7 to 1) idle yes, cruise close, but high RPM street bike stuff at full throttle 13.7 to 13.9 will make it pull better without killing mpg, high compression high load stuff on the dyno I have seen good power at 12.9 to 13.7 depending on the bike and engine type. Your street bike shouldn't be throwing coal, but a little richer makes good power, end even though your using a wide band use clean plugs often and read them they are your best indicator. I've never spent $400.00 to tune a set of two carbs and have built bigger twins close to 100hp. inline 4s nearing 200hp
'00 SV650, '00 GSX1300r, 91 EX500, '85 CMX250C, '75 XS650.