TDI-tuning.co.uk have one now for the 184PS unit in the GTD (plug in box), it's £289 and increases power to 239PS and torque to 495Nm. Considering it for my new GTD (due early Sept). My dad ran one of their boxes on his MK5 GT 170TDI PD for 3 years/40k miles with not a spot of bother and a 10% increase in mpg (power up to 200PS with it on).