why upgrade carbs? to tune a bike it needs heads gas flowed, free flow exhaust, hotter cams and then you might consider changing carb to maybe a slide carb which gives a snappier response for racing purposes.
usually to go faster, it depends where you ride. around town lower gearing at the expense of top speed, higher top speed fit a fairing and may be raise gearing slightly. twisties, get decent tyres to maintain higher speeds on corners (depending on rider ability)
I have seen off modern 400's on the lanes of cheshire riding round the out side of racing leather clad pocket rockets, but i reckon it was rider experience that held them back! straight roads it was harder but it was all part of the fun!
different again for track racing.