It might depend on your state too. In Ohio the have the useless E-check emmisions testing. The only thing they do to check the cat is look under the car. They don't even bend over to look, they just take a mirror and look for it. I am planning on taking the cat out and putting a straight pipe on it. Then taking an old cat, cut the top from the bottom and strap it to the new pipe for e-check purposes. Then if it passes good, if not I will go home put the cat back on and go to another testing facility. If you don't pass they just tell you to get it fixed and come back. Plus you only have to get it done every two years. I also want to get it dyno'ed bofore and after the cat is removed.