What capacity value should I choose for the tone capacitor?
The capacity is measured in nF (Nanofarad). You can take the values from the circuit diagrams or you can experiment for yourself. A higher value results in more high cut when you lower the tone pot (the sound gets a little muffled). Besides the classic 22nF capacitors you can also use a 10nF capacitor for a very delicate adjustment of the highs.
How important is the quality of a capacitor?
Do NOT use cheap capacitors! A simple ceramic sheet condenser from your local electronics parts shop is not intended to be used in top-quality electric guitars. I recommend the so called Orange-Drops or even better: Vintage Oil Caps.
Does the quality of pots matter?
Do not underestimate the influence of a good pot. I recommend products from CTS (USA) or Göldo (Japan). You could also go for a pot by the manufacturer Alpha. A resistance discrepancy of up to 10 percent is acceptable – larger offsets can already influence the sound spectrum in the highs. In general it can be said: 250kOhm for single-coils and 500kOhm for humbuckers. A lower values will cut the highs. A higher value will let more highs come through. Try and experiment what suits you best.
Does it make sense to use coil-splitting?
Yes and no! A humbucker that naturally already comes with a good high spectrum (i.e. Classic PAF, HB38, Classic Blade), i would not split. You would end up with a very thin, less cut-through sound and almost undefined sound. Meanwhile, high-gain-monsters like the NOwaxx Goliath or Distortion can profit a lot from coil-splitting.
How important is a "treble-bleed"?
A treble-bleed to retain more highs will fight the symptoms but not the cause. I you loose too much highs when decreasing the volume (with the volume pot) you should first check cables, amp, effects and the electronics of the guitar. If the loss of highs is still too much I recommend a parallel connected combination of a capacitor and resistor to the input and output of the volume pot (i.e. 470pF, 200kOhm).
Rule of thumb:
Higher capacitor value = lower loss of treble.
Lower resistance value = lower loss of bass when you decrease volume.
How about compatibility with pickups of other brands?
In the "jungle of the thousand pickup manufacturers" every one does their own thing when it comes to the direction of winding and phase coherency. In case you experience phase problems or hum in combination with pickups from other manufacturers, I will of course try and help you with my experience. And if you want play it safe, just send me your existing pickups upfront. I can make them all play to together really nicely.
What does DC resistance mean?
The resistance value of a pickup cannot give a reliable judgement on the sound of a pickup. The DC resistance is not only defined by the number of windings but also by the thickness of the wire and the geometry of the pickup. All these factors make DC resistance a very sophisticated topic.
Remember: The DC resistance value only gives meaningful insights when you compare similar pickup types (i.e. PAF humbuckers or 60s single-coils).
Do pickup covers influence the sound of my pickups?
Just to let you know: For NOwaxx pickups I solely use metal covers made of white copper. This material has absolutely no influence on the sound of the pickup.
But: The use of covers increases the distance to the strings (about 1mm). The pickup seems to loose some volume. Additionally the screws have to be moved out slightly which influences the symmetry of the pole-pieces.
Conclusion: The sound reduces in volume and lacks some highs. The pickup sounds a little softer. If you are looking for that cut-through sound you should refrain from using covers to achieve a more direct and whacky sound.