Recognizing the Protection of Motorsports Act of 2021 or the RPM Act of 2021 This bill authorizes the modification of a vehicle's air emission controls for vehicles that are not legal for operation on a street or highway and are used solely for competition. In relation to the exemption of competition vehicles from anti-tampering provisions, the Environmental Protection Agency (EPA) is prohibited from creating or authorizing a database of vehicle registration information that is required to be consulted at the point of manufacture, sale, installation, or use of parts or components. Additionally, the EPA may not require the registration of a vehicle, or part or component of a vehicle, by the manufacturer, seller, purchaser, installer, or user of the vehicle. The regulation prescribed by the EPA regarding the exemption must include certain components, including a description of the reasonable conditions for the applicability of the exemption.