Before...
After
That is a MagnaFlow 3.0" exhaust on a 2.4 Sky with GMPP intake and otherwise stock.
If you're not making over 400whp, 2.5" is fine and, according to MagnaFlow themselves, the factory 2.5" piping really can't be improved on.
The muffler can though and this is the muffler MagnaFlow uses in their Sky exhaust.
The MagnaFlow 5 X 8in. Oval Straight-Through Performance Exhaust Muffler 12265 is engineered to enhance your ride with a healthy helping of our signature exhaust sound and dyno-proven performance thanks to its free-flowing straight-through perforated stainless steel core wrapped in stainless...
www.magnaflow.com
You want that part number. Our mufflers are transverse mounted like the 2002 Camero (which this is for). The pipe at the top of the muffler in the picture is the inlet and the two on the bottom on either side are outlets.
A muffler shop can weld that into your current piping then either reuse your stock tips or add tips of your choosing.
Probably the most budget minded quality exhaust you can buy.