Downpipe is complete and I also replaced the horrible compression style clamps with 3" v-band clamps. Next up is the wastegate, which I decided to route back into the exhaust. I'm going to mount the wastegate on the underside of the manifold (since there is room), that way all pipes will be nice and short.
Old downpipe for the Tbird IHI compared to the new downpipe for the GT2871r:
Old leaky junk vs. v-band