As Jerry D said, a stock muffler and exhaust is in the same place. I don't have any engine mods as my stock 2017 SL is plenty fast enough for me and I don't like loud. However, cabin heat, especially for the passenger is a well known issue. I didn't see it coming and found out real fast that riding on an 80+ day was intolerable. I added a full cabin carpet/mat kit as an insulator and added a real hood vent in place of the plastic fake vent to let engine heat out. These mods alone made a HUGE difference in cockpit heat. It still gets warm inside so I am considering adding some more firewall insulation and am investigating cabin venting. Airwings don't fit my ripper windshield.