[Eric_Oz_S2]

Besides ending up with wonky afr's, the other problem with a "mechanical" tuning approach is you can't adjust timing. Rrfprs go hand in hand with mechanical distributors. And believe me, you want to be able to retard the ignition on these engines to get both performance and safety. If you log knock with standard timing and say 7psi boost, you will see that the dme (s2, 968 and turbo) pull a lot of timing. Without knock control you will end up with detonation.

What also happens with higher ful pressure is you affect the injector spray pattern. Go to high and you loose power as the injectors stream instead of spray.

Another problem is that rrfprs are mechanical devices that tend to vary pressure over time as the rrfpr wears.

No argument that they are a "cheap" solution (assuming you don't factor in possible engine damage), but arguably they are not value for money given the abundance of used injectors on the market and cheap tuning tools.