Hadn't been under there since I bought it to figure out the placement, but I bought one of these to make it easier:
https://www.pegasusautoracing.com/pr...asp?RecID=6939
And then bought a 19mm (if I remember correctly) drain plug to fit the bung, which I'll drill & tap to give me the right size female.

 

Well Puttie, figured out my other gauge, Zex has a new Nitrous Bottle Level gauge:

http://www.zex.com/zx/zextm-nitrous-level-gauge.html

Not exact levels, but close enough, since Nitrous volume is measured by weight & not pressure, the pressure gauges will only really tell me "it's safe to use at this time" not how much is really left, even the estimations made by this gauge will make things a lot easier than having to constantly take the bottle out to weigh it. Fuel psi gauge will go back up on the dash where it was & the new one will go in it's spot, should be to me before the w/e.

 

Was it difficult installing the boost gauge sensor?