I don't have warranty on my GT-R. I spoke to Sly, he said the car is like a brand new car that came out the factory, logs also say that has never been launched or abused, oil never over 110deg C, so he advised I shouldn't bother with the warranty. Bellhousing, steering lock and headlights replaced under warranty in the first three years.
So the "horrendous costs" in my case are about £1000 / year. Obviously plus tyres, pads, petrol, insurance, tracker and road tax.