IMO, depending on the exhaust, do a tps reset, give the exhaust/ecm a learn in ride and have at it. Your bike will be fine...BUT if you increase airflow by switching exhausts and air filters, your bike will not be running optimally. Doing both does not necessarily make your bike run lean either. You should remap to get the best performance out of your bike. If you are just going to do the exhaust, and can be happy with the way it turns out, more power to you. It's not going to hurt anything. but like I said, for optimal engine life and performance, the bike should be remapped. In my opinion anyway