Will a Sports Exhaust cause long term damage to the cat?

[London GT3]

I ask the question because the popping and banging, which sounds fantastic, is presumably unburnt fuel being exploded in the exhaust. I know that when my son regularly induced a similar sound on his Focus ST that he needed a new catalytic converter after 20,000 miles or so.

Does anyone know the construction of the exhaust system to know if this will be a risk?

[NBTBRV8]

I don't think it will be a problem, it is just that the standard system hides the popping and banging. If you haven't changed anything mechanical or fuel related just having less back pressure won't hurt anything.