Good luck on the taking pictures of cats. If nothin else you could just weld cats to the outside of your testpipes. I don't think they do this. Too may cats are tucked too high on cars. :) BUT, they do have these trucks out that can take measurements of your emissions and WILL send you tickets if you are out of compliance. I wonder if I get to use an excuse since in Denton county I don't have to have emissions inspections? hehe Doubt it.