Add chorizo to it, it really adds extra flavour.

Yeah actually a combo of pork and beef is great. I've often added pork cheeks to mine which are dirt cheap.Try it with pulled pork as well, I either smoke before hand on the BBQ 6 hours ish then shred up and add to a chilly mix, this gives a great smoky taste.
or just add a lump of raw pork shoulder to the mix and cook out, should take 3-4 hours maybe longer then remove shread up and stick t back in.
Add chorizo to it, it really adds extra flavour.