Hi Dirk. Yes the concentration of cars is definitely in Johannesburg. It is a pity really as Cape Town is similar in some ways to the Cote d'Azure. The perfect place for convertibles and some of the most unbelievable driving roads. I went to University there and still miss the place.
Interestingly enough, the main South African Ferrari agent is based in Cape Town. Their wbsite is www.ferrari.co.za
Johannesburg is the hub of all business in the country so it follows that the concentration of expensive cars is up here as well. In terms of Ferrari, there are some pretty exciting cars (F40, F50 and one 288 GTO) but in the main, there are no really special cars (not saying that the abovementiioned aren't special) - i.e. collectibles.
The Ferrari club has a track day at Kyalami once a year and it is a pretty awesome event - usually 10-15,000 spectators attend and it is run very well. I love going on the track but since my accident I am a little hesitant as I will not be insured. Also, when on the track I find it difficult to drive with restraint and almost inevitably find myself pushing as hard as I can after a few laps. I raced in the Porsche challenge and the Porsche club time trial series for the past few years. In those events the aim was to go as fast as you can - I guess that as soon as I am out on the circuit those feelings flood back - it's hard to show restraint.
I see you are from Belgium, have you driven around Spa?