I recently put a Custom in my Jackson RR3 and find it a pretty good sounding pup.
However, tonight I played my Jackson SL3, with a JB in the bridge, then plugged in the RR3 immediately after with all the same amp settings.
It's very noticeable that the Custom is much less powerful a pickup. I had, for some reason, assumed the Custom and JB were about similar in terms of gain but clearly not.
Or have I wired it up wrong?!