Lizard Skin undercoating works wonders for protection and sound...had truck done years back, MY A4 is as well...The z will need it too....f'n tire noise is worse than I have ever encountered, which should clear up w/ my new purchase a bit going with some 18x9's non-staggered to get neutral round these corners

 

In my daily driver Mazda3 I removed the interior and I used Second Skin Spectrum spray on the whole interior, doors, floor, roof, trunklid, wheel wells, etc.





I also used Second Skin Damplifier butyl mat on the doors, roof, wheel wells and trunklid, and some generic (read ebay) 1/4 inch thick neoprene closed cell foam over everything to kill the rest of the noise. The neoprene serves the same principle as Ensolite, but is much less expensive. (sorry no pics)

I dont think I am going to do this with the z as I would like to keep the weight down, and IMO it is pretty well dampened as is.

 

wow^ great work there