Miller Mountain High Performance is the culmination of decades of experience brought together by the renaming of Performance Specialties and the new ownership by Miller Mountain High Performance in 2021. The shop originally founded in 1994 is now a blend of old school techniques and next generation, new school technology. Miller Mountain High Performance is the culmination of decades of experience brought together by the renaming of Performance Specialties and the new ownership by Miller Mountain High Performance in 2021. The shop originally founded in 1994 is now a blend of old school techniques and next generation, new school technology.