Copy of reply my dealer received from Mazda this morning on this subject...
Good morning John , I have checked and this is only for the US market , uk cars under go rear end crash testing as part of homologation, and may wwell have stronger/thicker pipes used.
Hope this helps.
Regards
Paul Martin
Technical Support Engineer
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Mazda Motors UK Ltd
Victory Way, Crossways Business Park, Dartford, Kent, DA2 6DT