With those nuts added to the Crossfire threads I'd be surprised if the injector end protrudes far enough in to the manifold, so I'd check that out. Do you have an elbow fitting for the nitrous feed to the D-Block and either way do you have a restrictor fitted?

Your system is almost the same as I have John. I also have a minimax but stock ecu.

Initially my feed pipe from the nitrous pulsoid to the distribution block was about 4 times as long as the fuel feed pipe. But then I found out that the engine had an initial lean hit at lower revs, especially at high nitrous shots. The nitrous was getting earlier into the engine than the fuel. Jetting the car helped a bit, but not enough in my opinion, so now I have repositioned the nitrous pulsoid further away. The nitrous feed/fuel feed pipe length is now approximately 20:1. The initial lean hit is gone now although the car is running somewhat rich at the topend now, but it`s safe.

also, I suggest keeping your fuel pipe coming from the fuel pulsoid completely horizontal. fuel doesn`t like to flow uphill after the fuel pulsoid.

I suggest you play around with feed line somewhat to feel what the engine likes.
It made a difference in my case.