Just thought I'd drop in here to give another thumbs up to DTUK's boxes. (Andrew I'm jumping ship from AON - same username)
I was running a red box on my Astra which is not as advanced as the Stage-2 system that I'll be adding to the Golf as soon as I get it run in

I'm hoping someone can, at some point, find some more info about the clutch rating on the GTD to ensure there are no issues later in the cars' life with the higher torque output.