i have a 2004 Z71 5.3L, will it hurt the motor if i strait pipe it? right now i have a Flowmaster Outlaw on it.

 

Are you talking about using straight pipe to replace the cat? If so, it won't hurt your motor directly. The O2 sensors won't get a right reading and it'll make it run rich and by that diluting your oil and putting more dirty crankcase air back through your intake. So you can go with an O2 simulator, but they will stop working after a short period of time. Your best bet is a high flow cat.

 

it shouldnt hurt ur engine to straight pipe it, but i would definetly leave on ur cats. you'll get a great sound if u just take out that flomaster