I think the F40 is maybe a bit "bugged" at the moment. It's on an older build of the tyre model, I think that and the stupidly high default pressure just makes it impossible without a lot of fine tuning. I've managed to get a setup where I'm just about keeping the tyres warm but I've really got to push damn hard to keep it there. It's definitely handling in a predictable way and stops well for me at this point though.
iBert - are you finding the same thing? I'm getting closer to your time but just can't match you in the corners. Especially in the latter 2 sectors. Looking at S1 the graph makes us look neck and neck until Eau Rouge where you just carry much more speed, would love to know what your line is there. Seems I'm braking much later into Les Combes though, but that just isn't enough to even match you in S1!