Mustergutachten means, that you get a sheet of paper on which the power, emmission, dB... is noted, that you can report the results to you insurance and 'register' your car again with the new power. I really don't know how to explain it better... you know what I mean?
In Germany it's called TUV Mustergutachten, you can go to the TUV and the modification will be granded and written into your papers.
...alex
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Alex
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