The DTUK box was going to be the first mod when I get my S3, but I don't think its as good as the hype suggests. Its not that easy to fit, and although its not a cheap eBay resistor in a box, all it does is increase boost? I was under the impression it adjusted fuelling too since it goes into multiple sensors. I would rather have a proper map than the risk of running it lean.
It's still a glorified resistor, just because it might be digital rather than analog and have a few more bits, it's still just taking an input signal and in/decreasing the output.