I did a custom exhaust to my '06 with LS3 heads, headers, cam, straightpipes, etc. I basically kept the majority of the factory SS 2.5" pipe, then fabricated a custom X-pipe with an extra O2 bung and some mandrel bends to connect two Flowmaster 40 series SS delta flow mufflers with 2 4" SS tips. The stock exhaust hangers came in handy as well. At first, it had a decent amount of drone around 1500 - 1800 so I fabricated two 1/4 wavelength resonators (~38") out of 2 1/2" SS and AL tube and installed them just in front of the mufflers. This pretty much eliminated the drone and toned down the exhaust note at idle. When I open it up, under throttle it screams beyond description. Definitely recommend a custom job if you have the skill and time or $$$.