There is a company in Wilton, Torque Technique:
www.torquetechnique.co.uk/
who can probably advise.

Tarka has a single oval silencer under each running board, nothing at the back. The 1 into 2 finishers are a bit restrictive at the end.
I am wondering about a slim glass pack silencer and new end pipes.

Peter,
66, 2016 Porsche Boxster S
No longer driving Tarka, the 2014 Plus 8...