Ok so my catalyst was stolen off of my 99 sunfire. But my question is which option would b more benificial to the performance of my car straigh pie in place of the cat or putting a glass pack in place of where the cat was cuz I had a cat back exhaust but I also know that 4 cylinders need a cirtan amout of back pressure to work properly so advise would b appriciated thanks

I would say that depends on your states laws. In Virginia, we're required to keep the catalytic converter. Personally, I went with a high-flow cat, and then a glasspack after it. The glasspack/resonator really helps with the noise, a lot, and makes the exhaust sound a lot less raspy.

High flow cat wouldn't be bad, depending on state law. If it's not required, if your catback is a little raspy I would throw a resonator/glasspack in there (just for sound), if it sounds okay I would just throw a straight piece of pipe. Back pressure won't be an issue in this instance. Unless you're trying to run a 3.5" exhaust on an N/A car you'll be fine.