Questions on cat food and stinky BMs?

The odor is due to the ingredients to some degree. Generally a raw diet or grain free diet is best. Some ingredients that often contribute to the stink are corn and fish. It doesn't have to be the most expensive food, just a higher quality food. I like Taste of the Wild, which is actually cheaper than some junk foods like Science Diet. Felidae makes a nice grain free variety, Wellness, Blue Buffalo are some other good options.