Yes i searched, and found an informative thread, here:
https://www.rx7club.com/2nd-generati...-motor-397811/

Here is my situation. Second rx7, I believe it originally belonged to a member on here, Slava. Old Risky Devil car. Anyways.
It had 550cc s5 injectors, and 750cc s4 injectors with resistors wired in to the secondaries. It was untuned, so it bogged at 5k. I finally got paid, but I needed a quick fix for this weekends drift practice and chose to just throw in my s4 550cc injectors I had lying around. Just threw em in the secondaries and left the resistors. Car runs amazing now... Except you can feel, smell, taste how rich it is running. Idk why all of the sudden. I have an n332 rtek 1.5 laying around, I thought maybe I could hook that up? I'd just need to change out the tps, afm but what exactly am I doing about the wastegate and the OMP? Seems like a lot of work I know, but I have an s4 motor laying in my yard I can pull from.
Any help would be appreciated.

 

I believe most of your questions have been answered by the thread you've posted.

 

Is an extra N332 rtek 1.5 worth sourcing S4 sensors and wiring, then splicing half the car? No. Just use an N370. Is that what's there now?

If you removed 720cc secondaries and put back 550s back in with a stock ECU, or course it will run better up top. A stock ECU will dump more fuel if it thinks the injectors are smaller. You would find it running much less rich under boost, but idle and vacuum mixture would remain unchanged.