my mac catback hits the rear sway bar going over bumps and i was wondering if there are any negatives to removing the sway bar til i get some time to rework the exhaust? thanks.
You have other choices. You can have the tailpipes adjusted by a good exhaust shop. But, easier and at no cost to you is adjusting the tailpipes. First, you can adjust the tailpipes length-wise by loosening the clamps at the mufflers and pulling the pipes out a little bit. You don't need much for clearance. Secondly, there is clearance to be had by turning the tailpipes clockwise or counter-clockwise.
Without a rear bar, you'll probably notice more body roll in the turns and as 5L5 said, more understeer if you push the car to the limit. The change will be subtle.
The rear sway bar can also help even the loading on a hard launch, but I'm not sure how much effect that has when running street tires.
A MAC catback has a couple of places you can make adjustments. Should be something you could fix pretty easily yourself. Also, are you sure its hitting the swaybar? I have heard of them hitting the axle tube, but not really the swaybar.