BMW has Alpina, Hartge, AC Schnitzer. Mercedes has Brabus and Carlsson. VW/Audi have APR and ABT. Storied brands that have built expertise with specific brands over decades.
Now that the Koreans are building cars that at least look like they're fun to drive, are there any emerging tuning companies specializing in sprucing up the performance/handling of these cars? Seems like there'd be demand for such a thing.