Let's think about this for a moment.

What is the MINIMUM injector pulse for a 19 lb injector?

What is the MINIMUM pulse for a 60 lb injector?

Answer: The MINIMUM pulse for a 60 lb injector is going to be a significantly smaller portion of it's overall ability. Because the injector is so much larger, it has a much lower minimum injector pulse than a smaller injector. The EEC doesn't know this. So...

If the stock EEC is expecting 19 lb injectors and sees that AFR is rich, what will it do? It will reduce the pulse to what it knows is the minimum... for a 19 lb injector. With a 60 lb injector in place, that's going to be a LOT more fuel.

Now let's say that I have a calibrated meter, stock EEC, and 60 lb injectors. This "calibrated meter"

fools the EEC into thinking there's a lot less air coming into the motor than what there actually is. Let's assume for a moment that I manage to get a good idle out of it (this is hard but let's assume). I blurp the throttle. The EEC sees this and instructs the injectors to increase pulse by 5%. So here's the question: What is 5% of the max volume of a 19 lb injector versus the max of a 60 lb injector? Tip-in problem anyone?

Then there are injector slopes. I (the EEC) am going to increase my duty cycle from from idle to WOT throttle. I do it in increments as the motor increases power out and RPM. Let's say that I'm going to increase pulse at a rate of 5% per 100 rpm. Again, what is the difference between that 5% coming form a 60 lb injector versus what is expected from a 19 lb injector?

Something else to consider is the resolution of the meter itself. The ideal setup would be to have a meter that uses the FULL 5 volt range to indicate ingested air. Since the meter is 'fooling' the EEC by taking a smaller sample of the air then resolution is diminished. Perhaps it's only using 2.5 of the available 5 volts and a change of 200 CFM of air is condensed into half a volt instead of across 2 volts. This makes small power changes much less accurate. This can also cause drivability issues.

Tuning is pretty much essential when the differences are this large. I've gotten away with 30 lb injectors and a ehem.... "calibrated" meter. Going much larger than that without a digital tune makes drivability the suxxorz.

Even if the car seems to run well with these setups they at at least need to be verified through dyno testing or data-logging.

The quoted post above is accurate.