im basing this solely on the exhaust market when i owned my 350z...there were a number of exhausts available mainly from the 700-1200 range..

plus there was always the option of a custom made mandrel bent system with a number of options to use for a muffler

not doubting the ones on the market for the rs4 but why hasnt anyone even entertained going the custom route especially if its going to be cheaper.

im talking about catback..

They'd much rather just buy an exhaust from a trusted exhaust company. But, yes, a custom CB can be done for this car for about $600-$700.