I've been messing around with both the Mach1 and SB schematics in DipTrace and having lots of fun with them. Great circuits. You can see how the designer built the later pedal from the earlier architecture. The Southern Belle can get pretty gainy for an OD and sounds good like that. What would you add to it to take it into full-blown distortion territory? Put a boost circuit before it? Different clipping diodes to ground or VRef after the feedback loop clipping? Higher value pots? I may breadboard a few things but thought I would ask the crowd for their wisdom too.