if it helps - my nt16 setup AFTER breaking it in:

low speed needle is set at 2.5 - 2.75 complete turns out from fully screwed in, at that position the screw head is flush with the throttle arm too.

high speed needle is set at 2.75 complete turns out from fully screwed in.

this motor and tune setup lasted me a very long time, must be 10 or 12 gallons or so over a couple of years. remember each engine is different, but that should be somewhere near ur correct tune too... well, it should be at least.

(be very careful when screwing the needles fully in - stop as soon as u feel resistance or u will damage the needle)

hope that helps