I think this comment is selfexplanary.
The only question coming up is why the MINI Service in Japan then should do a service at a MINI with e.g. a REMUS exhaust as all the exhaust systems are obviously too loud for the Japanese. I do not get the sence to be honest. There is no logic.
The other question coming up is whether your friend will be treated differently with an exhaust from AC SCHNITZER. Also this exhaust will be too loud. May be the MINI Service will be different IF AC SCHNITZER is also a partner from MINI Japan as it is in Germany.
Or do I miss the point?