Big Muff Pi
The Electro-Harmonix Big Muff Pi is well known overdrive for a lot of different reasons. In the DIY world the main reason is that it has so many variates that there is not really a true or false schematic. Each batch of the pedal, when manufacture, were built with different components since availability was an issue. This is why I have only linked the GeneralGuitarGadget page because they use the same 2N5088 in all of their schematics. I am not sure which is the closest to the real deal, but here you go!
2N5088 – Big Muff Pi (one example)
Project: www.generalguitargadgets.com/projects/17-distortion/108-big-muff-pi
SCFXGuide 