When I built the SedanKamm for my Suzuki Swift, I used a 2x6 standing on it's side to help bring the angle closer to the ideal 12-15 deg, and it worked really well, I am sure something like that could be done on the 914 and make a big improvement. The roofline looks like it already tapers pretty well, so a Kammback should really show improvements!
__________________
|