any stock part on US mustangs has no german e-sign and is just "quasi" (inetwa) assumed to work. but many replacement or upgrade will work and be accepted by TÜV most probably if the parts are from same, similar or stronger car model, and if the parts are genuine Ford parts , e.g. with a fomoco or mustang sign. e.g. I just got all legal TÜV papers for the 19" wheels. because they are from a much stronger 2015 Bullitt, because they fit and because they have a fomoco sign inside and are official ford performance part. same is the Brembo kit. so no TÜV issue
