Thank God I found a noodle recipe that doesn't take me 3.5 business days to make.
I know the recipe says 1 chili pepper, and some people have recommended adding chili oil, but truthfully, you add chilis until your ancestors tell you to stop. There is no correct amount. Ghost peppers (or ghost pepper oil) would do lovely in this recipe.
As a side note, the bean sprouts were a little overwhelming. I'm going to cut them down and come back to this recipe with an edit when I remake them. (And I'll add a picture!)