Recently I removed some of my supply registers (located on second story ceiling w/ duct work in attic) in order to paint the ceiling. The air handler fan was running and I noticed that it seemed like I had a lot more air flow without the register in place. They are 10x6 (fed by 6 inch flex) stamped steel two-way with multiple closing vanes.
Are these registers considered to be excessively restrictive? If so, is there a replacement that I should consider?