The true NYC original. The Electro Harmonix Big Muff Pi Guitar Effects Pedal is the distortion that Hendrix and Santana, up to the top contemporary guitarists and rock legends, rely on for its rich, creamy, violin-like sustain. The Big Muff Pi was the first of many overwhelming successes for Electro Harmonix, and used by a long line of music legends, it's not surprising why the Big Muff has been reissued.