How to increase high frequency at Gibson Studio LP?

[Hiwatts-n-Gibsons]

Inexpensive fix:

Swap in 500k volume and tone pots.
Swap the neck pickup capacitor for a .015.

That will definitely give you a bit more clarity and treble on the bridge, and a quite significant amount more on the neck pickup currently in there.

More expensive fix:

Swap in an HB sized P90 bridge pickup, and something like a Seymour Duncan Dynabucker, or TV Jones T Armond neck pickup. No need to change caps or vol/tone pots.

I have the above pickups in an SG and a LP Standard, and they are fantastic. No lack of clarity, and plenty of muscle.

 

[gary buff]

Actually...back to the OP.
I've never heard a coil tap or split I'd give a nickel for.
I thought I did once and it turned out to be series/parallel.
That sounded cool, could be a worthwhile mod and could give the treble/clarity the OP is looking for.

Me neither, big reason I never got into PRS guitars. The split sounds on the 24-fret models were somewhat usable but the volume loss was annoying; those on the 22-fretters were useless to my ear.
Too bad, they played and looked great and build quality was superb. I tried to like them, I owned 4 of them at different times and sold them all.

 

[djd100]

One trick is to remove the screw bobbin screws which gives a little more of a single coil character, and you can also replace them with stainless steel screws if wanting to keep up appearances.