I think it would make it a S6 Plus + lmao.

The AAN is a fantastic motor, I've had 2 URS4's and 2 AAN Coupe's, both swapped by me. With that being said the sound an unhinged 4.2 twin turbo makes is purely amazing and the RS6 has won me over on that.

I love the C4 Avant body, and I think a 4.2 with either a twin/single top mount setup peaking out of the hood would be perfect. Theres plenty of room