My first thought for a rival gang would be Cubans, since there is such a large Cuban population in Miami. Or we could go just generic Latino, I guess much like the Mayans on SoA. I'd almost like to do something different. If we want to go racial, maybe Asian or Russian or something. Or we could go less racial, and it could just be a rival group from a neighboring city wanting to edge into new territory, and since the club is sort of new they pick us to try to muscle out. Just a thought.