Throttle cable will interchange from nt to cns if you have a decent amount of adjustment on the cable slack dealio on the throttle...
A lot of people drill more holes in all the air cleaners.
It probably helps a bit.
Builders with far more experience than I have said the transfer ports are the limiting factor on a china girl. So, it's probably not gonna need a huge carb or air cleaner.
IMO
If I installed an expansion chamber exhaust, I would certainly be looking for a superior carb.
The nt is much simpler than the cns, and I do think it's basic engineering is better.
However, I do think the cns can be made to dliver a little bit more power... if you try really, really hard to get it dialed in !
IMO, it just becomes a matter of diminishing returns.
For myself.
Some folks just love to tinker, and everything about these chinagirls is easy to work on, and dirt cheap for parts.
Have fun!
rc