In an effort to reduce emissions, increase drivability and/or prolong the life of the engine, most automakers spend an exhaustive amount of time balancing performance and usability on the factory engine computer. Before jumping headlong into modifications, one of the more effective ways of boosting output, particularly on turbocharged engines, is to have a reputable shop perform a reflash on the factory ECU or to install a piggyback computer to eek out any extra power left on the table by the OEM.
Naturally, tweaking some of these parameters may bring an otherwise law-abiding engine out sync with local regulations and this fact has garnered the attention of German authorities.
Since these systems are difficult to detect, even by trained technicians, the General German Automobile Association (GGAA) has enacted a new law that requires any firm that changes an engine's computer to have the modifications certified is seeking to educate and enforce both the public and aftermarket tuners on the legality of ECU tweaks. If an engine's computer has had its parameters changed, and brought out of compliance, the vehicle can have its operating permit revoked. Additionally, the GGAA is requiring owners of vehicles with ECU modifications to inform their insurance companies, and there's little doubt that these owners will see a significant increase in their premiums.
We're all for responsible tuning practices, but anytime government agencies get involved, both annoyance and expense is bound to follow (we're looking at you CARB).