Kschu,
Track condition change too much during the day. Heavier shock oil works good, like 700W, HB blue in day time, silver or even gold in front in nighttime is fast. Till now it's hard to say as I use only one set of tyres the last two days so maybe with new tyres my car will be different again.
Are you attending the Futuba Cup this weekend?
Keep you posted.
Jilles