you can check the k or even have the tuner load a different uprev map but I think you are having the same issue that I did. My fuel pump assy(housing where you put your fuel pump in and holds the regulator) was bad. We suspected it had a crack or a clog in it, so we replaced it, and no more issues.

After they were able to dive into it they finally found that the MAF is pegging out at 4.99v at about 7100RPM, something I worried might be happening after reading about Mr. Squeeze saying his car was getting close to maxing it out with the upgrades he did to the Stillen kit as well. At this point I'm just waiting for Sam to get back to me about some questions I had with their upgraded MAF and will likely be ordering that shortly.

So for futur reference, on a Stillen SC kit Motordyne ART pipes, 9psi pulley and the 928 motorsports impeller will have 725cc injectors running at close to 80% duty cycle and max out the stock MAF at around 7000RPM

Is that both MAFs hitting the same voltage?

yes, both are hitting 4.99 volts at about 7100 RPM according to the tuner. I'm not sure how they didn't notice this earlier but they have now and it seems I needed the injectors one way or another anyways.