i agree, just figured that is what she wanted, if you can, id drill it. ive had 2 overflow tanks now and the next one i get will for sure be drilled, i hate having my tank sit 5-6" off the wall just because the overflow box is behind it, such a PITA. functionality, the life reef overflows are the best. they guarantee you will keep siphon once it is started. another thing with HOB overflows is they tend to get a little loud, i had to put a DIY gurgle buster on mine.