I have the same Engineering affliction as you Dave and also tend to over analyze things. I will be running the same pump module and regulator as you with our EZ system. Everything these guys are telling you is correct. I will help them out with some more details of the system as supplied by FAST. I have also talked to the tech guys there and received very similar feedback as you. If you are asking anything out of the ordinary they tend to be vague. Anyway this should help some.
The throttle body as supplied has 4-88#/hr @ 60psi injectors. They have the system set out of the box at 43psi. At 43psi that is 298#/hr which should be 608hp or so at 100% duty cycle. Since you don't want to run at 100% duty cycle which is when the injector is open all the time, that is why the system is "rated" at 550hp. Which is around 90% duty cycle. Depending on your combination BSFC or efficiency these numbers can very slightly.
Now take what I just posted and forget about it. The system is set up to be EZ! The fuel module you are using with the 4th gen regulator is a bypass system. It just bypasses internal to the module. This helps reduce temperature and aeration. That fpr is set at 58psi. Just type that pressure into the hand held controller and let the computer do the rest. At 58psi those injectors will flow about 362#/hr which would be around 700hp give or take at 100% duty cycle. I would think you will be fine.
The only issue left then would be the vacuum reference. This Vaporwox set-up does not use one and it seems to be fine from the research I have done. I will find out for sure when we are up running. Sounds like you will get there first. Let me know if you don't mind.
I would say, install the Vaporworx set-up, install the EZ-EFI dead headed, set the fuel pressure in the hand held @ 58psi and hit the key. You can use the hand held to monitor the afr at tip in when you hit the throttle to see if the lack of Vacuum ref is an issue.
I hope this helps.
