This is perhaps my favourite circuit, but offline the AI cars are a bit like Sunday drivers! To make them a bit more competitive I added the following two lines to the .AIW file:
QualRatio=(1.1500)
RaceRatio=(1.2000)
which I added immediately after the line 'BestAdjust=(1.2000)'. This makes the AI more like racers - in a test against 8 Mini Coopers the quali spread was 9:56.29 to 9:58.807, and the best race lap spread was 10:03.55 to 10:06.764.
I'd be interested if someone else tries it and gives their opinion.