I personally don't find the Distortion fizzier than the Custom.
We all perceive things differently, of course. And "presence" doesn't mean the same for us all. But I usually think of presence in the way it works on a 5150 or a Recto in Modern mode. Like the uppermost sizzle the amp puts out. However, I know a JCM800's presence knob is actually controling a lower frequency than the treble knob, so even what "presence" means is up for debate.
I do feel like the uppermost frequencies both pickups put out is more or less the same in terms of "amount". You could go all technicall and argue resonant peaks and whatnot. The Distortion has a lower resonant peak than the Custom. However, no one is going to tell you the Distortion is a dark pickup. However, for me, they both feel more or less equally trebly, raspy, and sizzly, but not "airy" like a PAF-type either.
However, I do agree that the Distortion does come across as harsher because consider it doesn't have less sizzle than the Custom (perceivably, I mean), but it also has the JB's high mids on top of that. Add to that the Custom does have a bigger low-end, and yeah. That's why it sure comes across as that.
I do agree that the Custom might come across as "clearer" at first, but once you start dialing up the gain to match the saturation of a Custom-equipped guitar to a Distortion-equipped guitar, you're getting into a territory where the exta clarity the Custom offers becomes arguably negligible (IMO, of course). That being said, I've never had a problem with the Distortion's clarity. In general, I feel both Distortion and Custom are very "Duncan" in terms of sonic signature where even if they're high output overwound monsters, there is always clarity and high-end detail in the pickups' designs (compared to many DiMarzios, for example, which tend to have a rounder high-end and a bigger low-mid emphasis) with of course, several exceptions.
But overall, I don't find the Distortion fizzier than the Custom, personally. Harsher, yes, probably. Fizzier, not for me. Nor muddy whatsoever either. But we all like different things, of course.
