Putting an external overflow on a prebuilt tank

[blacknife]

I was thinking of putting an overflow on my 33 and adding it to my system but I am not sure the best way to do it.

the best suggestion i can get from the net is to pull it apart and cut one pane lower for coast to coast.

I want it to be quiet as the tank i have now is noisy as hell.

so i have a couple other thoughts:

internal just the pipes going in, 3 pipes all facing up but cut at different heights for a herby

or only a small internaloverflow perhaps an inch or so wide drilled through the side and have all the plumbing in an external overflow.

anyone have any better idea's?