I use R888s on my Pug 205 Mi16 and my Cossie when on track - not sure if they are any use to you?

They're not full slicks, but against normal road tires I reckon they are good for at least 2 or 3 seconds a lap, plus they actually last REALLY well on track. I normally kill road tyres!

I can get R888s at very good prices (due to the quantity I buy) - if you PM the sies you're after I'll get you a price

Cheers
Simon