I just came across this thread so I missed all the discussion up until now.
My car was a standard 2012 Duratec Plus 4, mainly because, at the time the factory would not sell me a LH drive Plus 4 SS.
At my request it was the first Plus 4 Duratec that was fitted with a Plus 4 SS exhaust system. Other than a heap of suspension problems with that car due to incorrect front springs and the dreaded sagging leaf springs I also had continual emission problems.
First the factory supplied and Borghi fitted exhaust wrap. That helped but it was not the final solution. Under warranty a new cat was also supplied. I then fitted individual throttle bodies and an Omex ECU. That helped a lot but after about 50 to 60 thousand kilometers I started getting exhaust smell and realized that the catalytic system was failing.
I was then advised that the size of cat was suitable for, at the most, a 1600cc engine!
Following this advice I fitted a better quality and larger cat.
By the way I do not find the sound of the TBs too loud but perhaps the cam on the SS makes a difference.

Peter

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