Make that 3...
the CNS is a good carb but it's NOT fun to tune... and if you don't have the right intake manifold for the CNS you'll be fixing air leaks every other ride.
The other deal with the CNS is that it's only 1mm larger than the NT speed carb so there's no significant gain with it other than a bit more tunability since it has a regular idle circuit and idle mixture control. It works nice when it's tuned, but it's also high maintenence compared to the stock NT or NT speed carb.
Maniac is also right about the stock intake.. it's only 13mm and putting a bigger carb on this intake won't give any gains. If you have the aluminum shorty intake it can be bored out to 16mm which will be slightly noticeable with an NT or NT speed carb installed, but even with the CNS installed on this bored out intake there wasn't enough difference in performance for it to be worth the trouble keeping it from leaking.
I've had mine up to 42mph with a regular stock NT so just get the jetting right on the NT after the engine has broken in and you'll do just fine. The SHA carbs work pretty good also and will give a slightly noticeable increase so if you're still looking for a better carb, the SHA on a shorty intake that's been bored out will give decent trouble free performance once tuned, but in my opinion, unless you're going up to an 18mm carb or bigger with a matching intake, the gains from these smaller carbs just aren't worth it compared to the stock NT.