Jim - I just noticed something for the first time about your setup. Where you have the hose bracket attached to the copper pipe, those look like screws holding it on that go into the pipe. ???
If so, screws into pipe equals flow restriction in the pipe
Won't make a terrific difference, but a 1/2 degree here, 1/2 degree there all adds up
BTW, any luck in your search for ducting/shroud/fan stand off material? And don't downgrade your setup, you did some really nice work with it
