Re: Need humbucker recommendations for metal
High-Output/Distortion Class pickups (DiMarzio SuperD, Duncan Distortion, et al) - those above 12K, came about as a means to push the input signal at the front of the amp when pedals alone either couldn't, wouldn't, or didn't do it well enough. While Randy Rhoads' recorded lead tones pretty much set the standard at the time, his rhythm tones both sucked and blew at the same time because he was using a distortion-class pickup through a Distortion pedal (not Overdrive, but actual Distortion), and had the amp raging. It was a wall of white noise.
Meanwhile, Tony Iommi was still chugging away on P-90s and PAF-voiced pickups in the 8K range or below, and delivering killer crunch and wicked balls.
I mean, Into The Void, man. That opening lone-guitar riff is still the heaviest thing recorded by one guitar.
If you're using a JCM800 and nothing between the guitar and the amp except a cable, you might want to look at a Distortion Class pickup. For anything else, go with a medium-high (10K tops) pickup and you'll have more clarity in your chords, more punch in your palm mutes, and more bite in your solos, especially if your amp already delivers the goods and you just use an OD pedal for solos.