Well you are absolutely fine in terms of not causing damage to valves or damage to the motor. Concerns should be heat and possible fire to the bottom of the car where the pipe will dump to. Then the noise of course. You might want to put a thread out to see if someone will lend you their stock cat back or something like that to get you by.
Originally Posted by granny
I will have a down pipe and that's it. I have heard of people running just the down pipe but that was in the lower 48s