Originally Posted by 370Ztune

We've been producing aero parts for GT-R and Evo X here in SoCal, so I know what molding fees cost and what's necessary to setup and what each piece can cost.

Most of the Japanese tuners purchase cars from the manufacturers for their demo cars. They often get access to the cars before they are released to the general public, so that they can begin R&D early.

To produce an aero part that looks good and fits, it makes sense to have an actual car for production. When these companies make aero, they design the parts much like the OEMs do with hand-sculpted clay on the actual car, from which molds are made.