To Get a expression with these types of outsized relevance in car culture, "JDM" is really an acronym for a reasonably monotonous phrase: Japanese Domestic Market. It refers to things built and meant for sale and use inside of Japan (i.e., not for export). This involves all the things from https://elevemotors.com/product/chevrolet-camaro-ls-16-20-oem-2-0l-turbo-engine-motor/