Owning a May 09 build Skoda Octavia RS 2.0 TDI (CR170), I've heard that the ECU's have been encrypted which makes it hard to reflash the ECU without sending the ECU away for "modification"
I've come across the Diesel Performance UK site that has a module that plugs in under the bonnet - has anyone heard good or bad things about these - see link - Skoda Diesel Tuning