Envirotest/AirCareColorado has multiple sites around the metro area. It's basically a state run monopoly unlike back in the day when you could take it to most any shop that had a certified tech. They will check to make sure you have all the emissions equipment(stock or aftermarket) that came on the car, that there's no CEL/codes, and that it passes the emissions test. As long as you still have all your equipment (even if it's aftermarket), aren't throwing codes and can pass the dyno/sniff test you should be good. BTW, if the tune is removable, I'd probably remove it a week or so before testing.