Exhaust was starting to get loud on my '01 LW300. Not surprising at 150K miles. Found a failed flex coupler between the Y pipe and upstream muffler. Friend at a local shop cut out the coupler and welded in a new one. There's still a minor leak, probably a pinhole in the weld. Will let it run in a bit and leave some deposits where the leak is. can't find it right now. Only hear a whistle on heavy acceleration. Good news is that I got charged one hour labor @ $95 and his cost of $45 for the joint.
I am an electronics guy and have repaired tools and consulted on stuff for the repair shop. In return I get repairs at cost.