Well it took 2 full days, a lot of sweat, some tears and even a little blood but I finally got my 90g to a noise level that I can live with! Thanks so much for all your guys suggestions...I tried every single one of them!! In the end I didn't need to modify the HOB overflow (not counting the folded towel trick!!). The problem was too much flow. I installed a ball valve and cut my flow from the pump by about 1/4 and did some fine adjustments to the black overflow box height. It's now running with not much noise at all and no gurgling!! I'm pretty darn proud of myself. Thanks again for all the help.