Does anybody have any real world experience with any of the piggyback tuners for the Q5 TDI's after the Fix. I am talking about the Chipwerke, Race Chip, Tuning Box and/or a few other brands that all offer very similar products and claims. I would love to hear from people here that have actually used them - preferably with positive results. It seems many of them are based overseas or sell primarily overseas but I want US based experience. Thanks for your feedback in advance.