I work for a camp with multiple vehicles that take children into the back-country for back-packing trips. Among the vehicles is one lovingly referred to as "Lil' Boy", a 2003 Excursion with the 6.8 V10. It also has upgraded exhaust so it is a bit more meaty sounding than normal.
About 30 miles into the back-country, a moderate size pot-hole (typical for the grooved-out half gravel/half paved road) knocked the vehicle pretty well. All of a sudden, I heard the very loud revving of an engine. I was following a Suburban and it slowed very quickly so I figured it had downshifted and I was close enough to hear it, but I immediately realized it was from my own vehicle.
On the side of the road, I looked underneath Lil' Boy to see a broken welding point after the exhaust manifold. We were about 10 miles still from the trail head, so we marched on, with an un-muffled engine note. It was rather obnoxious, but it certainly fit the personality of the beastly Excursion.
Upon the return trip (13 miles of 7-10% downgrades and switchbacks) I discovered that the scream of a Yeti is actually the exact same noise produced by an un-muffled 6.8 V10.