how big of a dif. did they make on your car (if you have one)

 

None, I had one and set it to stock pressure. I bought it because it was cheaper than the GM one at the time I was replacing it. Where I needed more fuel, it was done with changes to the EPROM. As far as I am concerned, the AFPR is just a crude EPROM fix. It changes the fuel delivery throughout the band not just at the spots you need.

 

ttt

 

I pretty much agree, but if you don't burn your own PROMs, an AFPR can be a helpful tool.

 

For $350 for the first chip and $150 for each mod from www.fasterproms.com or anyone else who does a truely custom chip, you can get better performance. Why waste time with a AFPR which all you are doing is enriching the entire curve whether it needs it or not? If you increase the pressure to little, the ECM will just shorten the fuel pulse width to compensate. You would need to bring it outside the range of compensation which would make the WOT great but the rest of it too rich. In that case, why bother with EFI? Why not go carb where you could stick on a set of larger jets when you need WOT and smaller jets when you just do cruising? Just have a carb for all occasions.