Unfortunately most suppliers stopped importing ANSA systems years ago so finding one would be difficult... they stopped bringing them in because quality was poor (i think the original ANSA brand was sold off to another manufacturer).
Centerline advertises ANSA systems for some Fiats on ebay but they are $$$... so maybe give them a try...
Otherwise a custom system is the way to go... you can buy Borla mufflers here like they use in the US and i know they sound good so maybe thats an idea.
'74 105 GTV 2000
'71 240z, Defender 110 Td5