Wayne Parham Messages: 18835 Registered: January 2001
Illuminati (33rd Degree)
With very few exceptions, I suggest to everyone that they do not modify cabinet dimensions unless they are willing to perform acoustic testing and possibly to make changes adjusting for anything they might find.
In so doing, this defeats the purpose of even using a particular design, except maybe as a starting point for a new design. I definitely wouldn't go through all that effort just to use an existing cabinet. It is much easier to build a new cabinet than it is to re-design, which may require several test cabinets and/or crossover changes on the way to finding the final design.
The reasons are described in the Pi Speakers FAQ. See especially the last five links in the "Cabinet Design" section of the FAQ.