I fitted Revolution 1's in my 5 GTT a few years back. I found them to be incredibly supportive but uncomfortable for anything more than a short journey (30 minutes or so and I used to get back pain and a numb ass!). They were also a pig to fit as the subframes Corbeau supply with them are way to low so that even on the highest position I could just about see over the steering wheel - this meant fabricating some spacers to raise the seats up. They also make your visibility a bit poor due to the head supports with reversing becoming a real challenge.
They did ,however, look the absolute buisness!