If anything, i would try the mastotron mods or maybe try out different transistors, but its hard to beat this circuit as is. Its a fuzz face style circuit, so in general, you should keep it simple. Ive tried about 15 different transistor types in this circuit in different gain ranges and found i liked the stock configuration the best. I even tried bc108's and 2n2222a's, which are generally my favorite silicons, but the 3904's had just the right amount of bite. Ive always wanted to build a germanium version of this pedal, but havent tried it yet. I bet it would sound great, but it would be hard to find just the right set of transistors. Let us know how the build goes.
