You could always go this route: https://blog.1aauto.com/2003-audi-rs6-ls1-engine-swap/

In all seriousness, one of these "big hp" threads from a new owner pop up on a semi-regular basis so we're all a bit salty. I'd honestly love to see someone mod the hell out of one of these cars but to my knowledge it hasn't been done yet because of what everyone here is saying. If you do attempt it, please post a bunch of pics. It would be fun to watch!