These parts are not sufficiently homologated for the use within the purview of German road traffic laws. Therefore, use within Germany is only possible on the race-track, for show and exhibition purposes or for restoration of veteran vehicles. Which parts are legal for veteran-restoration, depends on the vehicle's age and must be seen about with the autorities in charge.

Outside of Germany, the homologation and a possible use in road traffic must be seen about with the local authorities in charge.

These exhaust-systems have less back pressure than the stock system. This causes a lean fuel mixture, the fuel metering system should be readjusted.