AFPR's are a total waste of time and money.... if your car is stock. Let's think about this for a moment...
A stock fuel system is controlled by the vehicles computer,
which regulates how much pressure and fuel is delivered to the injectors. If you install a AFPR you can "dial in" the desired amount of fuel/pressure that the injectors deliver..
Sounds simple.. But what if you have stock injectors that are still being controlled by the computer ? The computer is programmed to deliver a set psi, so now that you've got that AFPR installed and cranked up say 42 psi (or more) and the computer say's "no I dont like that" it does not deliver any more fuel to the injectors. Hence your still running a stock system. Now on the other side of the coin, if you to replace your injectors with higher volume and reprogram the computer then there will be a slight performance increse. This is just the tip of the iceberg, it goes alot deeper.
I installed a afpr ,cpu chip(setup to use it) and 36lb injectors in my 383 tpi with a ported manifold and runners.vette runs MUCH better now and no longer leans out at full throttle , keep in mind that afpr is part of the system and without changing the system its not going to do much by itself hope that helps
Depends on the year of the car. The earlier C4's can benefit because you can modify the amount of fuel delivered during open loop as the ECM will just use a pre-programmed injector pulse width. On later computers, the BLM numbers are also used to adjust injector pulse width when you go into enrichment mode. An increase in pressure will deliver more fuel for a given pulse width, but the ECM will maintain 1.47 air:fuel ratio in closed loop by dialing back the pulse width.