The NMCA Technical Committee has made changes to the True Street class rule set. Specifically, the committee has changed the Exhaust rule to: EXHAUST SYSTEM Any Exhaust exit location permitted. Exhaust system with mufflers required. On Turbo applications, the Turbo acts as a muffler. Updated 2020 NMCA Rules can be found here: https://www.nmcadigital.com/2020-event-info/class-rules-payouts/