For £25 I doubt you have the right pots then, if he has changed the pots, they probably aren't the best quality, if he hasn't then you need to.
There will be 6 screws in the pickup ring, the corner ones hold the ring down, and the middle ones adjust the height of the pickup, turn clockwise to raise.
I don't think more gain is going to make things more chunky neccesarily, play with the EQ a bit to see what it can do, they have quite a few tones.