I just bought a used Crewmax 4x4 5.7L, which already had a dual exhaust system. It has a tiny Flowmaster muffler about a foot before the rear axle. At 1700-1900 RPM, the sound and vibration is very intense (at least 120 db) inside the cabin. Once it goes above 2k RPM, its gets quiet. I absolutely love this truck, but the sound is driving me crazy after just a few days of ownership. The tips stick protrude 2" beyond the rear bumper.
I've been looking on the forums to see what people do to reduce the noise, and found the following solutions:
1. Add weight to the pipes after the muffler. This can be done by welding on some heavy bars or clamping on 10 lbs
2. Install Dynamat sound dampener to the floorboard.
3. Replace the exhaust system with another system. Potentially find someone to trade with
4. Cut or bolt on different pieces to "tune" the system. This one seems easy. Perhaps, I can just put a bigger muffler on the existing system, or add a J-pipe resonator.
Here are some photos. I'd love to get rid of the crazy resonance and vibration, but keep it sounding mean when I start it and really gas it. I don't want to pay a bunch of money, but it's my daily driver, so I'll do what's needed. I'd really appreciate any ideas, links, etc. that can help me out.
Exhaust by Alan Shepard | Photobucket