This is just some quick advise, not in-depth.
First thing to check if your replacing injectors: Resistance
If there low or high. If there’s low resistance and you install high resistance, basically the car will not start. Usually you can remove a resistor block and your up and running.
If there High resistance and you install low resistance you will damage your ECU and more.
Most stock ECU’s that can be re-tuned can handle up to 1000cc injectors (Not all).
Most modern aftermarket ECU’s will handle very large injectors like 2200cc.
The issue is not under power but at idle with big injectors.
There are a old Bosch injector (1600cc) that had such poor response time that even with a good ECU at idle was around 10-1 AFR(0.7 Lambda) on a 3.0L six cylinder at 1500rpm, They were used allot on Rotaries.
Modern injectors come with injector data, This data in a modern ECU improves tuning time and end result. AFR/Lambda are able to be setup and controlled with flex fuel (E85) and trim table’s like fuel pressure drop.
I have a favorite injector price vs control vs injector data, it’s the Bosch motorsport 1000cc. From NZEFI.
There is one other injector I also rate very highly and it’s the Bosch motorsport 1650cc It’s a lot more expensive but if you need it, you need it.
Fuel injector sizing. I don’t like to run an injector over 85% duty cycle.
So working out what size you need is quite easy at injector dynamics and you also can order the injectors direct from them as well. Lambda usually is between 0.80-0.85 under full throttle and 1.0 at idle, Ethanol “0” petrol or 85 for E85.
Fuel pumps are a big problem when it come’s to tuning, there are so many non genuine pumps being sold, It’s costing customers a fortune in dyno time.
What i recommend is an in-tank pump or external bosch 044’s for most street/strip and track day cars (Race/drift cars need completely different fuel systems)
Fuel pressure regulator is always recommended when upgrading the injectors and fuel pump