Once in a while i see someone saying that they’re buying a flat chanter, just the chanter, not the rest of the set. Is this because they’re planning on playing the flat chanter on their existing CP bag, or is there a way to tune down CP drones to be, say, in C# or B? I can’t imagine one can do this with regs, and I wonder if even the drones are possible…
No, it’s not possible to tune the rest of the set down. People often buy just a chanter because they can’t afford multiple full sets, but as you can imagine, this is not nearly as fulfilling as having the whole kit. 
djm
Isn’t that the truth! Thanks a ton.
Some people can tune down their drones, but that usually requires changing the drone reeds, as playing concert drones in C# or C can result in instable drones which change pitch according to bag pressure or which just shut down.
Also, with a C chanter and D drones (not retuned) you can play tunes in E minor and E dorian. Liam O’Flynn does this on the Seville Suite in the tune The Humours of Barrack Street.
I did manage to get my top two drones up to ‘E’ which worked quite well with E maj stuff on my Williams ‘B’ chanter.
Djimbo.