[2 Yoopers]

I did the pvc in the return vents, that helped the flow a lot. I also purchased the Jet Stream air out vents from dwincorp.com. They offer them in a same size direct replacement style with a shorter inner sleeve that does not protrude into the narrow duct to far.
They also offer a larger version which is what I used. I removed the old restrictive vent and sleeve. Traced a line showing the bigger hole needed on the ceiling.I used a dremal with a straight 1/8 carbide cutter to easily cut through the ceiling and the duct.
I then used the aluminum duct tape around the hole and duct. I installed the new sleeves and snapped the vent on and air flow greatly improved.