I just had two of these installed on my Mustang 5.0:
http://www.rpmoutlet.com/powercat.htm
From the butt-o-meter they seem to work very well. I was thinking I'd replace the stock cat on the 911 with this unit as well. They only run $150 each.
What bypass pass do you all recommend me purchase to modify and add this on to? Or should I just run without a cat?