Spent Thursday at "The Aircraft Factory" in Johannesburg. Once again I was made very welcome. I was fortunate to go flying with Sean, in three different Slings during my visit. The first was the Sling4 ( ZU-TAD ) with the new Rotax 915 engine installed, I think I am the first Aussie to fly with the 915 engine. It has quite a few modifications to accommodate the bigger engine. The factory are re-designing the Sling4 specifcally for the Rotax 915 engine. It does get along very well, we were indicating 130-135 kts, TAS in the mid 140's. We then flew in a standard Sling4 which flew very nicely, even in bumpy air. Finally in a Sling2, which was my first flight in a Sling2, again the aircraft flew well, even with a takeoff density altitude7500'. Photo 1. ZU-TAD 915 engine and modified cowl. Photo 2. Water drums for load tests ( notice GoPro mounted on ceiling ). Photo 3. Standard Sling4 and the Sling2 in background.