Performance is in Bakersfield amd so is Proformance but they are currently closed, SoCal is in Valencia/Santa Clarita but they dont do repairs. Im not sure of any on the South Bay area but if you come towards OC and IE you have DieselTune in Downey, Metro Diesel Injection in Santa Fe Springs, Buds diesel in Huntington Beach (im not sure if they are still doing repairs but im sure they are), Domestic Diesel in Chino but they always have a waiting list, and Resurrected diesel performance in Lake Matthew's area.