I have made a similar chili recipe for my friends who aren't vegetarians. I make it without Tofu (it just freaks too many people out) and add another can of tomatos. Make sure your beans are vegetarian beans, many will use animal products to get the right flavor.
I also substitute the ketchup for a little less tomato paste (about 1 of the small cans). Thats by personal preference, I prefer a strong tomato flavor in my chilis and it helps helps to thicke the chili a little.

I'd like to try this recipe, but what is masa? Can it be left out?