Those Holden V6 motors can make a lot of HP if you do the right things to them. A pair of turbos would have you embaresing most of the cobras out there.
I saw a GN Buick V6 Turbo charged powered Cobra in the US a couple of years back ind it was a weapon.
Turbos do a good reasonable job of muffling the exhaust too.
Welcome to the forum Martin.
Cheers