Mark Shead put 4 1000 cc injectors, iirc they were Siemens on my car and said that was pretty much future proof, I would ask the mapper what brand and size they would spec for the Engine that they are going on as I suspect the way the mapper does the car may determine what to go for. Mark likes a lot of boost on his maps, other mappers do things their way...

I think low and high impedance needs to be matched to the ecu type too???

What power are you going for? Interested to hear the spec.