here,s why, Many thanks for your email.
With regards your enquiry an adaptor is not available for the installation of the high flow downpipe and sports cat onto the OE system.
Due to the diameter differences and the restrictions within the OE system the heat build up within the downpipe and sports cat would cause damage and premature failure of the catalyst assembly, especially if used with additional hardware changes and software changes.
Regards
Leigh Ravey