on another thread we had been talking about removing the cats in the engine bay. today i went down to a local shop and got an estimate for custom downpipes(removal of the cats in the engine bay), j-pipes and true dual exhaust. The shop said that they would charge me 650 for all of this and two flex pipes and also making the flanges to fit the place where the cats go. Now he said the only problem that he would see, is that i would have no back pressure at all and that my car may start to malfunction. Now i know that might be a problem if the o2 sensors start to mess up or read things wrong. Now some one said that the only ones that are important are the one on top of cat. The other two i can buy those things two kill the o2 or to make it think everything is okay. Now i want input from you guys. Also he said that if i have no back pressure i mess up a valve. He said this because that is what happend to one of his clients?!?!?