The other side of it is my old S3 spent a day(!) on the rollers with the fuse pulled when Peter Link mapped the car,with no adverse affects.....this is the procedure MTM use themselves in Germany,its not something Kim came up with himself and decieded to give it a go.
I'd find it hard to believe that a German tuner operating under the strict TUV guidelines and procedures that they have,would advocate such a procedure if there was any element of risk involved,they are an ultra cautious,conservative shower after all.
