MAP sensor adjuster
Use the FPR for coarse adjustment and add a MAP sensor adjuster for a fine adjustment! Yes, I was skeptical too, but these things work. Tweek the voltage being sent to your Map sensor up to increase the fuel injector pulse width at wide open throttle!
My own Adj Maps with custom etched circuit board and the smallest components available, not hobby board junk.
Only .5 inch by 1 inch, tiny! $35 each.