if i run without the catalytic converter and no muffler will it in return hurt my cars engine and cause to much back pressure?
Do yourself and everyone else a favor and put a functional catalytic convertor back in there and run a decent muffler. Disregarding the legal aspect of driving a car with intentionally-defeated emissions equipment, your truck’s computer is designed to work with the inputs from the oxygen sensors both upstream and downstream from the cat. It will not run correctly without a functional cat. So, it will be worse for the environment, AND it will make less power. Quit being cheap and put the right parts on your truck. The muffler is primarily to reduce noise. Driving around without one is just asking to get pulled over. Getting pulled over without an intact exhaust syatem is a good way to get a mandatory inspection, which is a good way to get fined for gutting your cat. Seeing the pattern here?
