noisy cars in Switzerland

[AW10]

Some mates and I are thinking of a bit of an alpine tour later this year. Some of the cars have been de-catted and/or have rather noisy exhausts. Assuming we drive sensibly and don't take the p*ss in built-up areas are we likely to get any aggro from the Swiss police for the noisy cars and almost certain emissions failures if they were to be spot tested ? They're fully registered in the UK but as we know UK MOTs and testers are a bit more "flexible" than the Swiss are.