Quattro FF vs Nasal....Different AHI

I have a theory about my Quattro FF Mask. Since my F&P CPAP does not give me data, I periodically use my back up Elite machine to see how I am doing. It seems that whenever I wear my Comfort Gel Nasal mask with PapCap my AHI is in the 4.5-5 range....however...when I wear my Quattro, the AHI is 7-7.5. My theory is that to stop the Quattro from leaking I need to pull the lower straps tighter which in turn pulls my lower jaw back. This, I am assuming slightly closes off the airway. When I wear the PapCap the strap slightly pulls my jaw forward. (Leak Rate is near Zero on both masks). What do you think?

I think you are quite right.

I've been titrated with 10cm and started CPAP 27/12 with Quatro FF Mask.
Since then I'm messing with diferrent pressures (as high as 15cm) and Exhale relief level and becoming more and more frustrated.
The best I could is a AHI=12.5 / AI=2.5 / HI=10.

In my sleep study titration I've used a Nasal (Comfort Classic) mask and a pressure of 10cm was sufficient to stop any apnea.

I'm looking forward a nasal mask to see my results.
I'm quite right that the lower straps tighter pulls my lower jaw back and so the back of my tongue, blocking the air way passage.