2001.5 A6 2.7 and S4 exhaust compatability?

I know theyre two totally different cars. Same motor though. And I cant really see a whole lot of options for the 2.7t A6 exhaust. So can someone with experience let me know if there is a way to fab up an s4 exhaust to fit without getting too expensive? I know I can have an exhaust custom made mandrel bent from platinum for $10000 . Im not looking for that. Im looking to go cat back (after vast DP's) for a decent price. What do I consider decent? up to $800 or so. Really. Theyre just bent pipes.. I dont see $1600 for millteks as acceptable. They look great. But they reunder the car. so long as its stainless and mandrel bent Im fine with it. i could give too ****s how shiny it is.. So.. Can I fab up RS6's S6's? RS4's? etc etc.. thanks guys.. im planning on the vast downpipes.. high flow cats. cat back exahsut that sounds GERMAN.. Not civiccy.. I HATE that bumble bee **** sound. then Ill chip it.. I want my babys breathing first.
P.S. I dont care if i have to cut out the bumper or anything.
Thanks for reading