it sounds completely different running it before or after distortion. running it after gives you a smoother sound that alot of people seem to prefer – difficult to describe, but you’ll know it when you hear it. running it into distortion gives you that super gnarly deeppurple-type hammond grind; you know that nasty fuzzy mess in the white stripes’ blue orchid? that’s the sound you get running the pog2 before distortion. it’s my preferred tone, but try it both ways to see which sound you like better.

other than that, i would run it before the volume pedal. actually i would run it before everything except for a tuner (and maybe a phaser).