Hello. I think that a 24mm carburettor is too big for this kind of cylinderkit, which is not a racing kit.
A 21mm carb is quite enough, you can put another valve (I would advise the Malossi VL14, the best)
The intake manifold and doublelayer filter are not necessary, original manifold and prepared original airbox are really enough for this kind of set up.
If you want to increase your scooter's performances, I would tell you to change your variator. If you really want to stay on Stage6 parts, the R/T oversized variator would bring you a better accélération and a higher speed.