The Thunder Pup from UK firm Bigfoot Engineering is an overdrive pedal inspired by AC/DC's Malcolm and Angus Young.
Besides standard gain and volume knobs you get a toggle switch that offers a Big Amp or Little Amp sound - designed to deliver the sound of a stack with a 4x12 cab or an open-back 2x12 combo.
With gain to spare, clean boost is the first port of call with the Thunder Pup, but turning up the gain knob treats you to ever increasing levels of very nicely voiced amp-like distortion.
The Big Amp has more compressed distortion and bottom-end thump, plus a denser midrange than the Little Amp, which is more 'open' - think Plexi/Bluesbreaker. But both offer a natural Brit raunch that can go from mild break-up to full amp distortion with plenty of sustain.
If you're looking for overdrive and distortion with a British flavour, the two voices here provide versatility in a pedal that also offers crisp note definition and responds dynamically to your playing.