Hehe, the discuson on this subject made me curious and I decided to try the IROC.
The setup menu doesn't provide too many options. If I remember well, I've ended up with: softest springs front/rear - rear ARB decreased by one click - only little changes on shocks and brake balance 60/40.
Requires a smooth driving style, but lets you take the last chicane in a straight line going hard over the curbs.
And what I forgot to mention: avoid abrupt and extreme lift offs.

Cheers m8 and good luck on tuesday