I have been looking at tuning boxes and came across this one: CRTD2® TWIN Channel Diesel Tuning Box - Audi A4 2.0 TDI 175 Bhp / 177 PS / 130 Kw Does anyone have any experience with twin channel tuning boxes? It claims to be able to increase power by a whopping 30% but also better fuel efficiency of approx 10-15%. I assume that these are the ranges of the system, i.e. you can get that much extra power but fuel efficiency might be adversely affected. Or you could select increased fuel economy but power may be adversely affected? Basically, if I could achieve 10% better fuel economy and 10-20% extra power using the same setting, I would jump on one now!