I would have thought it would be made out of ABS plastic like the original. You would need some new side-skirt clips (easy to change) and some decent black tiger seal type adhesive for the other parts. Bit of a fiddle but, once painted and matched to the car, it makes the world of a difference. A real presence on the road if you're willing to make the investment!That's a very nice 166. A few people have used these guys for items and apparently they are very good. Not sure what they are fabricated from though so you might need to enquire. Probably fibreglass and not ABS so you'd need to be really careful with kerbs, etc!
Alfa 166 Zender-look bodykit [166_BKZ01] - €487 : AutoDS Team Poland