Ok, here goes:

I have a Nx Gemini Twin carb nitrous system. http://www.nitrousexpress.com/Pages/TwinPP.htm

I haven't plumbed anything up yet, mostly because I'm terrible with thread sizes. Could someone tell me what the thread sizes are for the solenoids and the plate?

 

If you have the solenoids pictured in your link:
Nitrous inlet 1/4npt x 4an (1/8npt x4an for the lcarbon fiber Lightning solenoids)
Nitrous outlet 1/8npt x 3an the supplied T fitting

Fuel Inlet 1/8npt x 4an
Fuel outlet 1/8npt x 3an T fitting again

Plate fittings are 5/16npt x 3an

 

Awesome, thanks man!