You dont need a rolling road to remap most cars as I sell them over the internet! - the checksums are the biggest problem these days. Long gone are the days when every car has to be re-mapped individually - unless it's had modifications from standard.
There is a local dyno that can take upto 2500 BHP - I use that if and when it is needed to tweek the programs initially along with some major tuners that I know in Germany.
I was shocked at how easy it was to get hold of one of these cars - I thought it would take months but they seem to be everywhere - at the moment!