I also talked to aaron a little on this.
Because i am going single now as we speak.
the MAP is fine but when you pass i dont remember but i think its 14.7 PSI the MAP is pegged on its scale so the 1JZ map is fine unless you boost higher then the fuel cut for that map.
I am looking into this a lot also i just ordered HKS 550cc side feed high impedence injectors from XS for about 130 each.
I have a GT35R but unlike most people who have T3 open or T3 devided or T4 open with .63 or .82 AR mine is exotic turbo combo it is T4 devided & DBB even though on a 1.06 AR trim after talking to 5+ companys SP & drift motion, ATP turbos, XS, Etc.. AAron 935 and the guys here know there stuff for now i am using the 1JZ ecu and 550's & 1jz MAP but once I go above 15lbs of boost I will for sure need EMS and a 2JZ MAP & verry close to needing a top feed with 600-650 CC injectors. to much above 6000 rpms with 20+ lbs boost will be unsafe.
We need details about the set up.
I know I am a major newb when it comes to single upgrades.
I think Aaron is right.
As well itr is right also but just to a certain point.
pics below...