I was able to spray some wd40 in there, let it soak in a bit, and then got them to start to wiggle. It was a PITA, but they came loose finally.
As for installing the new Agos, I coated the area where the pipe slides into the new mufflers, (where the spring will go that holds them together), and where the pipe slides onto the H pipe, with fluid film. Getting the heat shield hole on the pipe to be properly aligned with the two other heat shield holes on the muffler itself required me using a wooden mallet to "tink" the pipe a little to get all the holes to line up properly. If you simply align the pieces with the retainer spring in alignment, the holes will be a touch off.
If you want to call me I would be happy to talk. I'm EST here. PM me if you want.
John Henry