Its a Remap/ECU tuning, best mod you can do on VAG cars for about £500. On my Cupra I gained about 25bhp for £470.More imprtantly a load more torque. Basically plug a REVO Switch into the Serial port and can be switched on/off and tweaked. Undetectable to dealers/insurance companies when switched off.
http://www.revotechnik.com/products/sof ... x?pvID=583
£499 for 55bhp according to their figures