I have the RP200 and I set the pedal to control amp gain.With the "Hotrod"(Boogie) or "Boutique"(Matchless) amps selected,just backing the pedal up reduces the gain enough to get a nice purr for blues.For twang I'd try the "Blackface" model with gain around 70 or 80 and the compressor engaged and a bunch of treble.Good luck!