J. Jensen,
You can use V-band clamps. I have had some 3" ID clamps connecting the collectors to the exhaust pipes on one of my cars for more than 10,000 miles. They still look and function as new, and are pretty easy to remove and replace.
Here's the URL for the ones I use:
Vibrant Performance ::.
I had the flanges welded to the collectors and pipes by a really good local exhaust shop.
BTW, the engine in that car is a 557 stroker, so it does give them a workout. I ran the Daytona track last week with them using the 24-Hour Rolex course, and also take the same car to the lumber store.
Two interchangeable sets of exhaust parts could be practical...
Tom