Hi again Andrew,
I have not had Michelin tyres on a 993 but have had good experience on other vehicles. I would probably have tried Michelin on my car as in the past although expensive they do tend to give high mileage at the expense of ultimate grip, however although Michelin list a Pilot Sport in 285/30 and 225/40 with N1 rating I have never been able to locate a local dealer (I am in the West Midlands) with any available stock, they always say that they are on back order and have been ever since they can remember. I think that the fact that it has an N1 designation and has not been superseded with an updated specification (i.e. with N2 and then N3 etc) means that it is quite an old tyre now and unless they have a new production run, then all existing stocks may have been exhausted.
Nevertheless, if you can find a supplier with Michelin tyres to suit I think that they would be worth a try. As we all know they are a top quality tyre and the latest 997's are often equipped with Michelins.
Let us know how you get on.
Tyres on a 993 are very important and it would be good to build up a list of experiences from other 993 users.
Cheers,
Mark