Visual/Physical Inspection

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2007 GMC Yukon XL, 2007 GMC Yukon, 2007 Chevrolet Tahoe, 2007 Chevrolet Suburban, and 2007 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

Inspect for aftermarket or non-OEM devices such as, but not limited too; tailpipe extensions, headers, and exhaust cutouts. This could affect the operation and proper performance of the exhaust system.
Verify the exact operating conditions under which the concern exists. Note factors such as engine RPM, engine temperature, engine load, and frequency of concern.
Inspect the easily accessible or visible system components for obvious damage or conditions which could cause any symptom.