Not to claiming to know it all, but (keep in mind I have been taking electric guitars apart and putting them back together for 41 years and without parts left over for 40!), you have to understand that you can’t really measure “output” as that is a VERY relative term. I can tell you that D.C. Resistance (the only way the average consumer has to measure a pickup-with a ohm meter) is a measurement of the “resistance” of the coils. That is NOT the output, just how much wire is on the bobbins. Alnico or Ceramic magnets? Alnico poles, or Alnico magnet underneath the bobbins with steel studs coming up through the bobbins. ALL will have different “output”.
So… that having been said. I have 2 pickups for sale, the “hot” one is actually LOWER in D.C. Resistance that the original PAF. The “hot” one is 7.9 kOhms which is the one about which you are inquiring. The other one, which is a stock PAF from the 1970’s (the one you walked into a music store and bought in the box) is 8.2kOhms. The thing to keep in mind that, to me anyway,
RESONANT FREQUENCY, which some call “Resonance” is more important and that’s where the differing magnets come into play. This “Hot” PAF uses Alnico magnets as the “studs” (as opposed to chrome plated steel) and is going to have more output AND a bit lower Resonant Frequency. “High Resonant Frequency” is going to be like a single coil around 8-10 KHz which is a measurement of which freq band the pickup is most sensitive to. Closer to 10KHz, the brighter the pickup sounds.
A REALLY hot hum bucker will have a D.C. Resistance of 8.5 but with a high Res Freq is going to be as LOUD as a pickup with a lower Resonant Frequency (like the DiMarzio PAF, the “Hot” one is going to have a D.C. Resistance around 7.8 which seems “Less Loud” than 8.0 but (I am using my ear, not a measuring device) has a Res. Freq. of closer to 6 KHz which will have more “grunt” and “apparent gain” than the Vintage PAF which has a D.C. of 8.0 but a higher Res Freq of 7 or so and less gain.