Check this out. Just thought I would share it with you .
http://www.robietherobot.com/nitrousjetcalculator.htm
12.3 12.7 if that's on spray , to me that's too lean.
I would try free flowing at 6 psi..
My motor with spry is in the 10's and 12.9 N/A
22 mph Is quite a bit of loss . Good idea to tighten it up..