From what I could gather, you need to monitor the real time data on the Predator looking at your long term fuel trims. The target is to be as close to 0.00 as possible across the rpm range. In my case, it appeared I was running around +4.00 in a lot of instances, so what I did was to set the injector slope to -4.00 on both banks. That should have brought the averages closer to what is considered optimum.
Of course, I am a newbie at this as well, so take this with a grain of salt, subject to verification...........
