There was an article in the French mag Flat 6 about this car (February issue). It was originally meant as a 2.7S. The car was waiting to be officially introduced, even promotional materials were ready: the 1973 brochure shows a Signal Yellow 2.7S next to a dark blue 2.4S, a green 2.4E Targa, and a Speed Yellow 2.4T.
Then the CSI (as the FIA was known at the time) decided that manufacturers had to build 500 stock models to be allowed to enter Group 4 racing, and 1000 for Group 3. So they just dropped all the extra equipment and called it the Carrera RS. The rest, as they say, is history.
If I were any serious about collecting Porsche (read: if I could afford it

), I'd absolutely get it.
For the real car anoraks here, the trim around the front turn signals was black on 1973 production models, but it is rightfully chromed on this one, as this 2.7S was based on a 1972 model (notice the infamous "oil cap" where the gas cap sits on more pedestrian cars). They edited the pictures on the brochure, though: it shows the blackened trim.