I have searched and have not been able to verify the correct part number for the 2011 S6 lower rear valance (diffuser).

I have a 2011 A6 Prestige, (3.0T) with the S-Line front and rear bumpers (honeycomb style lower) and trying to decide between quad tips (needing S6 valance) or cutting out the rear most muffler adding straight pipe and using a 4" double walled tip on each side.

Also, does anyone know what size the exhaust pipe is... maybe 2 1/2" dia??