This is one of those "a picture would explain all" situations but my camera is at work and I don't know how to post a pic and my dog ate my homework :-). The band clamps I'm referring to are a wide strap about 4" long with two bolts to cinch them tight - see
Dynomax Performance 33226 - Dynomax Lap-Joint Band Clamps - summitracing.com for a pic. They grip and seal up okay but over a few years can slip a little and let the muffler twist slightly, for example, so I just loosen them, realign it all, and retighten every few years. The bolts are perpendicular to the exhaust pipe. Maybe I'll get enthused and try to get a pic this weekend, but don't count on it :-). Hope this helps.