mufflers for around the house use?

What do the ends of the headers look like? Are they straight, "race only?"

Go to a shop, get a piece of pipe that will go over your collectors, cut it in half, and then saw/ split two sides for 6" or so

Get about 4 big hose clamps, Lowes, etc

Then buy ONE big glasspack, and saw it right in half, cut out a simple sheet metal plug and takc in, and weld your pipe sections to the open ends. Trim off the outlets and you're done.