is there any source on these for a 99? I bought my car and it has no cats at all, and I dont want to put one on it. It worked fine but after I put my cat-back on the CEL started to come on for a catalytic converter efficiency code. Now I know that Casper Electronics makes them for Camaros and Mustangs and the like, but is there some source that I have missed? 
Member who somehow became The President of The SE-L Club
If you've taken out the pre cats on a Cali Spec car you need to use O2 simulators to trick the ECU.
www.o2simulator.com
www.o2simulator.com