They don't sell ANSA but I spoke to Chris (from my dodgy memory) and he cares about the sound of the good cars. Advised against expensive stainless becasue of the sound. There are sound files and pictures of their work on the web site. In the end I went a different path so I can't recommend them personally, but they did impress.
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.
Location: Lake Macquarie New South Wales Australia 00=V=00
A good quality exhaust is excellent and will last a long time, but you do not need to spend big dollars to get a nice sound, basically with Alfettas, GTV Guilietta GTV6 90 75, you cut out the rear baffle section, can't rust out on you if it's not there, run your favorite size pipe size straight thru from the first baffle section to the rear and put a chrome dump on the rear with a flare, you can tune your favorite sound via the dump size you put on, all this can be done including labour for under $200.00