I believe that the PA NVA is the best available. The nylon seals and fine taper threads contribute to my beliefs, as well as the availability of any single part from Randy.

The PA NVA is the best out there!  It is fine thread, and the collett to hold the setting works much better than the ST.  It only needs to be finger tight to keep the needle from moving since it has a nylon seal.  I would definitely use the PA.

The problem with the OS needle is that rediculous spring.  When the engine is running you can't hear the click.  You can move several clicks when one click in either direction is the difference between running away and the perfect run.  Not to mention if you actually need the spring (profile) it kinks horribly and looks like crud.  Also after time the knob and spring will come loose so it turns but the needle doesn't, or even better the knob just comes off.