Il me semble qu'il y a ça aussi ref:MUTE (SILENCER MUTE £8.00)
This can be used to reduce the noise made by an exhaust system. It cannot be modified in the way that the exhaust baffles can and is the correct diameter to fit tightly in side the 350cc exhaust pipes and the 350 & 500cc high level trials pipes that we offer.
Dimensions: Diameter 35mm.

If at first you don't succeed... fail, fail again !!!