You could put them in the MP1 loop which then gives you on/off control via midi (ie change patch on MP1 to patch with or without loop) and also control the amount of fuzz the pedal adds to the MP1 tone with the loop mix setting. Normally you would put them before the MP1 but in both cases you have to be careful about the gain, the pedals can add quite a bit of gain and thus potentially overload the MP1 input. There were (and still are) plenty of fuzz/distortion pedals way back when I stared to play, can't stand most of them. I got a better sound (for me) by cranking my 1972 Marshall 50 and then adjusting it's volume with a Tom Schultz power soak (as no master on the old Marshall). When I got an MP1 all that went away as the MP1 has plenty of gain/distortion and totally programmable, I'd (and still am) never been happier with the sound. I'd imaging the 3TM mod or similar would cope with thrash as it adds another tube, that's if there's not enough gain in your MP1 already.