If it's not really about tuning or wiring. Then it belongs in here.
what’s the best way to pair injectors for batch injection, I was thinking Opposite cylinder in relation to firing order?
Usually with batch fire the injector will fire every 360deg so there is little consequence how they are paired. In the case of a V engine I try to pair them so that you dont have all injectors in one rail all turning on at the same time as it can make fuel pressure less stable. It is nicer to have half the injectors squirt on each side, then 180deg later squirt the other half.
Isn’t having them all fire on one bank, banked injection?
Batch, banked, grouped, multi-point group, in most cases are just different manufacturers terminology for the same thing. Un-sequenced/un-timed injection with the injectors firing in 2 groups - usually every 360 deg and the groups will be separated by 180deg.