ProSpeed chassis are mainly focusing on GT3 cars: https://www.shapeways.com/shops/prospeed-slot-racing
Stefan is based in Germany and is working closely with Tamar Nelwan (the Flying Dutch) to create some unique chassis and pods for us that do it digital -
in particular, for DiSCA competitions (http://www.officialdisca.com/).
I have ordered some chassis from Stefan (Scalex Merc AMG GT3 and the Carrera M6 GT3). When they arrive will report on their performance.
Some other interesting items are the wings for the Merc, Bentley, M6 etc.: not only these wings are lighter than the original items but are also more flexible - which means they can survive even the hardest marshalling of digital racing.