The newer ZEX NMU's have a self learn mode, meaning that it learns the voltage curve of the TPS on your car. Lets say it doesn't produce 4.5volts like you say, it is still supposed to learn whatever voltage WOT is at and activate the solenoid then.

Interesting that you say that it wont work for the 97+ cars. I thought that by re-routing the FPR through the NMU it is supposed to kick up the fuel pressure by creating more vacuum in the line when the nitrous is activated.

I guess what I am trying to say is that I am not sure why you can't use a dry kit on his car. I figured that a 55 Shot would be well within the capibility of the stock fuel system of the car. Any more insight on this.