You can set the expression pedal to control different things on different patches with the Peak. When in 4PR mode, remember to select which patch (P1-P4) that you want to program. Then enter program mode. Then press EXP and turn on expression pedal for that patch. Set E1.CC to 7 (Volume). Save. Then with either PT or the stand alone editor, remember to turn on volume pedal. Save patch. Done. It's the same process to make it a wah, except you must also assign a switch (C1-C8) to turn on/off the wah, whereas the volume pedal would always be active in the patch. Hope that helps.