I talked to a muffler shop here in Greenville, NC and he said removing the back cats would trip the rear O2 sensor, what about the pre-cats??(I dont know what theyre called) Would removing these cause me to not pass inspection under the new laws?
i have changed some on chuckyes (chevy) that had pre and aft. o2 sensors, and yes you will get a code if they are not there and the engine will run crappy, best thing to do on a 96 and newer is to buy the pefromer exhaust made for the o2 sensors, they do make them and high out put cats and do some mods and programming to the truck to get the high output if that is what you are looking for. if it is just changing the exhaust, then buy the kit mad to replace the factory a lot of compines offer them and they are not really that cheap but it is the right way to go and pass the OBD II
I've changed my exhaust enough, I was just trying to find out why the Fords were different, thanks for all the help. My Dynomax Bullet is pretty loud, I just wish it would idle louder.
the before and after o2 is to make the engine run more cleaner, it gives more info to the computer to control the fuel air ratio: and if you wnat a louder exhuast you may be able to just change the muffler to a glass pack or just gut the muffler i have done that