[PNJSNAK]

Neil: Welded the reducer couplings to the side pipes and then simply put in a couple of stainless sheet metal screws into each pipe. Check the screws to make sure they don't back out, but after you run them a while enough crud gets on the threads and holds them in place real well. Make sure you put them where you can get at them from below. With the body on if they are on top, it would be hard to get them out. I did not like the idea of pop rivets, but I guess you could always drill them out to get them apart, and you will want to get them apart someday.
Jim
Jim