I'm new to the forums but I've been researching parts for my 2000 S4 for about 2 years now and i know how difficult finding those parts you're looking for here are a few sites that may be able to help.
www.goapr.com
www.ecstuning.com
www.wolfcars.com
www.achtuning.com
www.lltek.com
these sites helped me so i hope they can help you.