Bathy those are Schumacker fullspike yellows, about the only things that work at the Faversham track (wooden floor)....
I should be able to see where my car is on grass, the colour's bright enough and if I do lose it I'll just carry on driving til someone complains about me shunting them off the track...
I'm looking forward to getting the 501 up and running in next years outdoor series, should be a laugh. I'm thinking of getting an X6 to run in 2WD as well, I find electric so much easier and more fun than nitro, no mucking around with engines or anything, just plug the battery in and off you go...
-Steve