Hello Marc..Just wanted to follow up. As always you give great advice. I went back and remeasured. The clamps that connect the U-pipes to the muffler are 44.5mm (1 3/4) and the coupler that connects the cats to the U-pipes are 45mm.
I was able to get stainless steel for the clamps but not the coupler. The coupler brand that I ordered actually makes the Porsche coupler. They fit perfectly. I saved about $50 ordering these clamps. Hope this helps someone else. Again thanks Marc.