I wouldn't baffle the outflow too much because it could cause the water level in the filter to rise, thereby causing the water flow to avert the filter media. I had this problem with a power 10. I never did get it baffled correctly, but I'd have to agree that a tighter sponge would result in less water flow (speaking in terms of the intake). A tighter sponge would not only prevent water from getting through the gap between the sponge and the intake, but would also have smaller holes for the water to flow through, making it harder for the filter to suck up water, and essentially decreasing flow. Just think of a sponge as a bunch of garden hoses and put a rope around the hoses so that they're all kinked, and less water will pass through. Makes sense to me... I'd like to see it in practice first before I'd claim it actually works, though.