I am recently purchased a 2011 CTS-V for my wife for her birthday. What exhaust have any of you installed for a nice rumble without it being too obnoxious when cruising at 65 mph? This vehicle has the 556 HP engine. Probably looking for recommendations for exhaust after the Cats... not looking to install any headers or pull off converters. We currently have a 2008 CTS 6 Cyl and she wanted MORE POWER!! CTS-V...here she comes!!! I appreciate any comments!