Help! does anyone out there have any experience with inline fan mufflers?

My set is pretty standard. i have a elicent 6inch attached to the wall with about 3 feet of hydrofarm flexable wire ducting. its attached to the appropriate sized Phresh carbon filter thru a hole i cut in the ceiling. Now the noise that it creates is very good as far as inline fans go but its still not good enough. I was going to by a couple crates of eggcartons and do up the whole room but upon further study most sound engineers do not think that it works all that well. So i have found inline fan mufflers from HPS supplies i believe and they look nice for around 60 bucks. But before i by one i would like to know if anyone has used one and are they worth the purchase? secondly putting one on my intake fan would obviously cut the noise on that fan but would putting a muffler on the intake side of my exhaust fan cut the noise on that fan as well. i know its not an easy question but any info or help on the matter would be greatly appreciated.

Im sorry its called a htg supply 6 inch duct muffler.