The PI wheels on my car are 12x17 Campi clones, but I think they're the GT wheel clones.
I Know that PI sells some Campi clones in the same sizes.
They are aluminum, not magnesium though.
They DID make some really wide original campis, magnesium, but I THINK they were 15's, like 12x15 or 13x15, and hard to find tires for these days I think, AND I think the offsets were for the GT cars with wider stances (flared race cars).
Flared, wider stance or not, 335 rear tires look bada$$ from behind.