The X-pipe is better because it creates a better vacuum effect which sucks the air out of the exhaust system better (gain more hp). The Prochamber has good gains, but not as good as a quality x-pipe. Yes, the Prochamber will bolt up in place of your stock H-pipe. I would recommend one, they sound awesome!
i have a pro chamber and i love the sound and i noticed a slight gain. my brother has the bassani x pipe and it sounds to raspy for me. if you do go with the pro chamber try to use the manifold flange gasket that came with your car or get a new one because the on mac sends is junk