need knowledge
 

Does anyone know of any good websites to visit in order to learn as much as possible about sub enclosure design? THX!

There is a nice starter box design program here. WinISD is the first download on the right side under the programs heading. It's free and helps with some of the basics such as matching box size and port to a specific sub.

Or are you looking for more of a shop class type of site like how far to space screws, how frequently to place cross-braces, what glue to use etc?

I would be interested in any info that would explain why steps are needed and how it effects performance. cross bracing, port design, and I would never have thought of how far to space the screws. I will check out that one program you did mention above. THX!

Rockford Fosgate Site.

Box Tuning Wizard

These are a couple links that might help you out a bit.

I used them in combination to design my enclosure for an Eclipse 12" sub. Its only a few days old, as is the sub, so we're not able to crank it up yet. But so far so good. It's a very basic box, no extra support or anything.