Basically, the "Wizard of Oz" may have cut open, examined and copied an existing "Unicorse" exhaust design, which is probably much easier/cheaper to get hold of in Australia/Asia than here.
I expect that's also why they sell the "replicas" over "here", rather than "there", owing to risks around intellectual property - or whatever governs the original part.
All just wild speculation on my part, of course...
There is a lot of wild speculation there
We never hid the fact we made Unicorse replicas (or something like) for the 156 GTAs when we first started back in 2009, in fact it has Unicorse's name in the thread title. This is the sound people wanted, they'd heard it on Youtube but they couldn't get it mostly because Unicorse don't reply to emails, they are a very busy & successful Japanese Alfa Romeo race team probably with better things to do than politely replying to enquiries. I was one of these disappointed potential customers, I'd sent loads of emails over the space of a year, trying in vain to pay them £1200 for just a backbox at the exchange rate at the time. I managed to get hold of a 156 2.5 V6 backbox in the end by buying the only car in the UK known to have one - the previous owner had paid a Japan-based parts-sourcing firm to travel to & buy a Unicorse exhaust from their shop in Japan and ship it over to him at huge premium - over 2400 GBP for backbox & a pair of downpipes after duty & VAT in the end if my memory is correct, I do still have the invoice somewhere. I went to see Wizard for a decat section & custom mid-pipe making up, and we got talking about making a few exhausts for some of my GTA customers in the same style, seeing as there were lots of people eager to have one but unable to do so. But we never copied the original design, as the 2.5 V6 backbox isn't suitable for a 3.2 V6, its in the wrong bore size for a start and doesn't fit the tailpipe position on the bumper. Also the 2.5 tailpipes are undersized which isn't so much a problem for a 2.5 but is for the bigger V6. We spent every weekend for a couple of months playing around with different variations, seeing how changing the casing volume affected pitch, resonance, playing around with different tailpipe diameters to see if restricting or de-restricting the box could smooth out the sound, basically making a 3.2 sized box internals sound like my 2.5. We did lots of trial fitting the backbox at different angles to reduce the overall amount of bends in the system and even out the clearance through the tunnel and over the rear subframe, all changes made in Wizard's shed in Oxfordshire and then we would trek over to Bedfordshire and we'd trial fit them on my cars using AL's ramps.
The first batch of exhausts for 156 GTAs was a roaring success and we've been inundated with orders ever since, we started making them for other models as people started asking us to, but everything else is 100% our own design. I bought my first GTV V6 for us to build a prototype on so I could do some long-term testing, other models have been kindly loaned to us for mocking up purposes. There are now Wizard exhausts in 27 different countries and we've even sent a few systems to Japan, not surprising given our cat-back systems are less than a third of the price of a Unicorse at today's exchange rate - and no, there is no patents either on Unicorse's products or our own. People are free to imitate, I'd love to see anyone else get anywhere near as nice quality of construction, ease of fitment and exotic sound as we do for reasonable cost, nothing else on the market even from already well established exhaust manufacturers does
As you can no doubt tell I am immensely proud of what we do, we have put our hearts & souls into it working crazy hours in addition to our other full time jobs in the last 6 years to be able to make these exhausts so apologies in advance if any of that sounds overly defensive. If it was so easy just to 'copy' an exhaust we'd get them made in China and I'd be on my yacht right now.