you mean capacitors?
If you want to prevent treble loss, it's maybe a better thing to install treble bleed circuit than go up to 1M for pots
. Treble bleed circuits help recover some treble when volume is rolled down, but don't affect the tone when volume is maxed. If you get 1M pots sound will be brighter than with 500K at any volume settings. Many ibanez guitars have 330pF capacitor stock which works fine up to a point, at lower settings it gets brighter. I use kinman treble bleed which gives more consistent response.
As far as tone cap goes, 0.022uF is standard but for many people it's too much.
I recently installed 0.01uF cap on my RG prestige.
I wrote a little article on wiring, tone controls and treble bleed circuits, you may want to check it out http://diy-fever.com/misc/guitar-wir.../#treble_bleed