A GREAT box for thickening up single-coil pick-ups is the Demeter Fat Control pedal. It's a mid-boost. It also adds a bit of volume and gain, depending on where you set the one knob on the pedal. I love it. To me, it's the definitive "magic box". It can be subtle or quite drastic. Sounds great, has a buffer in it and it doesn't mess with your tone.