I have never seen a pedal get the kind of balls a good valve amp has, that might be a huge part of the problem there.

And yeah, your 8-32s aren't going to do you any good unless you can play like Petrucci. For just doing power chords it's not a good idea using strings that thin. If you want big rich meaty chords start packing more steel. 11s might be a bit big of a jump from 8s, you might want to try something in the middle like 10s.

Also, what type of pickups do you have? That could be it there. If you're using weaker single coils and he's using something like an humbucking X2N it's pretty hard to make up the difference in sound.