I put on the catback from a supercharged cobalt. Larger diameter pipe and higher flowing muffler, needs a bit of tweaking to fit, but is cheap used.

 

I have a Magnaflow axle back muffler welded to a stock 2.4L cat back pipe on my 2.2L, and I love it. The exhaust on the 2.4 was noticeably larger in diameter than the stock 2.2L, and I did feel a bit more pull higher up in the RPM range. the longer resonator on the one I have also gave my exhaust an nice smooth low rumble and tone. Mileage was not really impacted, probably because I'm in it a bit more because I love the sound.