What an ingenious little bit of plumbing! I have 2 holes in each overflow, so I don't need it personally, but I think a link to that should almost be a sticky somewhere. 
 
One thing I was thinking. What about eliminating the 2" standpipe inside the overflow. This should increase the flow potential and reduce detritus buildup in the overflow... just a thought. 
		
	
		
		
		
		
		
	
		
		
	
	
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