Confused: N20 usage gauge + window switch wiring?

[BBoyPersia]

Ok heres my problem. I have a gauge that can monitor and control all my n20 activity, but I only use it to monitor my bottle pressure and n20 usage through purge and spray. Here is the wiring diagram, youll have to make it bigger to read the writing if you cant see:
http://img200.imageshack.us/img200/3036/1002457.jpg

I understand the n20 pressure sensor wiring and the orange stage2 wire that taps into the purge line, my confusion is the yellow stage 1 wire and where it connects to. Its showing that it connects to the n20+fuel line which im assuming is the n20 controller, in my case the zex box. I run a wire that goes from the TB to WS to Zexbox. My question is if the yellow line taps into the line running from the WS to Zex. It seems like the only logical place.

[1FST4DR]

That makes sens to ma as well however the same wire goes to a relay as well,Does that guage need that relay to work?The Zex doesnt use a relay.IMO I would call the company to make sure.(Guage Co)

[BBoyPersia]

im not using any relays. the gauge has so many features that im not using just because i want to feel more in control. pretty much the gauge can read your fuel/oil pressure and cut off n20 if they are too low, turn on the heater when the botle pressure is too low and turn it back on till a certain level, theres just so much you can do that i dont feel like wiring and configuring. i just want it to read how much i use and let me know how much is left in my bottle, everything else i want manual lol.