Piper make a DPF-back stainless exhaust system for the Corsa D 1.3 90bhp - apparently FIAT provides the GP chassis and engines to Vauxhall/Opel for the Corsas, so... it should fit the Grande Punto, no?
I looked at getting the Remus exhaust. was thinking the same as you. unfortunately the mounting points and general exhaust route is different to the GP (according to a local exhaust specialist.)
and its GM (General motors) who provide the cars then Fiat/vauxhall provide the badges haha.
no problem,
Have a look at getting a custom built up for example 'long life stainless exhausts'
you get to choose the tip and usually what type of sound your looking for