Sure - I'm willing to give the Merc a try.
Thanks!
Cool, well here's my setup so far. I've been making it for another race I'm doing this week which has lower track temps so the setup is on softs - for this race mediums will be the way to go. Let me know how you get on! I'll probably have an updated version by Sunday, but for now (without mentioning lap times) this seems pretty quick if RSR is to be believed.