Mfg's box size/alignment vs. DIY?

[Marzen]

I've noticed after doing two cabinet designs for Rockford Fosgate drivers (10 & 12") that the mfg's recommended cab size & alignment don't jive with BassBox Pro's recommendations. Both drivers I modeled recommended a large ported enclosure based on the EBS results; yet the mfg steadfastly recommends a small sealed one. Am I missing something here? Discounting cabin gain for the moment, models show that it will exceed it's max cone displacement at around 50hz @ 80% max power in a small, sealed box like you see at Best Buy.
I have yet to tax my dual 10" subwoofer with a 250W plate amp in a 4cu^3 ft ported enclosure tuned to 28hz. SoundEasy models match up with the BassBox models as well. I would think 'car driver' mfg's would intentionally opt for a design that would perform well in a small sealed enclosure, hence my confusion.

[JonMarsh]

It all depends on what you want to do, and how careful you are. A sealed box for a driver will be less likely to wind up with warranty returns for over excursion. A well designed EBS alignment will put out a heck of a lot more low bass, but requires some care in design and construction, and should be used with a suitable subsonic high pass filter to prevent over excusion below the tuning frequency, where the driver will tend to "unload" from the enclosure, and excursion will rapidly climb, while acoustical output is rapidly falling.

~Jon