Maybe people are wondering what you're trying to achieve by altering the dimensions before they pipe up with their thoughts?
If it's a case of increasing the gain of the enclosure, trying to accommodate larger drivers or maybe restrictions on space available for the enclosure then fair enough.
In my case I posted a request for thoughts on extending the horn by folding it back over the top surface of the enclosure to increase the lower reach and possibly extra output.....at the end of the day just build it and see.....I've got half an inch of mdf dust on my garage floor so it's happening here.....wife says she'll bury me in the thing though as I've already built umpteen speaker boxes and what was wrong with those?