My two... liras: maybe carb with bigger throttle diameter wouldn't be better then stock 30 mm carb. IMO, with bigger carb, displacement of the engine and design of the motor head and valve train can not provide required speed of air-fuel mixture through on low and mid revs. As a result, only improvement you could feel on high revs. Better ask someone who's been dealing with carbs.

You can try to rejet your stock carb and experiment with needle position and see how bike runs.

Or you can try some 28-30 mm CV or slider carb with acceleration pump...

And I don't know what to say you about exhaust. I know - it is hard to find in Italy something that can suit you.

LeoVince, Jollymoto, Marving, Arrow, Giannelli, G&G, MIVV, HP Corse, Termignoni...