Of boosting safely. An adjustable FPR will raise the fuel pressure and normally the over the counter chips run a conservative timing and a little rich. Increasing fuel pressure would be detrimental on a basic setup. Now, I do have an AFPR because I didn't know if I was going to need a little extra fuel above what the 740cc injectors were going to give me at normal pressure when I tuned for E85 and all it got increased was 5psi above normal if i'm not mistaken.