Audio Systems: Subwoofers, fs sd, winisd

Question
Hi,
If a subwoofer is designed for SPL competitions does that mean that you can't use it for everday driving on the street.I want to purchase two of these http://www.sonicelectronix.com/item_5652.html#specs but I'm not sure if using it everyday would damage it, because it is designed for SPL competitions.
Thank you.

Answer
WOW that's a heck of a sub!
Using a sub designed for SPL as an everyday speaker shouldn’t damage it any.  When a sub is designed there is a balance of many, many characteristics.  eventually these characteristics amount to a balance between things like:

sound quality
sound Output (volume)
Box size and design
Cost
Power handling
etc.

Often SPL subs are designed optimally for being loud but not necessarily clear.
A sub designed for sound quality in a box designed to optimize sound quality will attempt to play every frequency at the same volume. And will play as deep as possible. And will resonate for the smallest amount of time after power is removed (it wont ring so to speak).
A sub designed for SPL in an SPL box will produce 1 frequency as loud as possible with as little power as possible. All other frequencies are sacrificed to add to the 1 frequency’s efficiency. Sound quality and resonance are not a factor in a design like this.

These speakers may sound great if the enclosure is designed properly for them to suit your needs.  Best thing to do is to find the small/thille specs (VAS, QTS, FS, SD, XMAX etc.) and plug them into a program like WINISD which is free here:
http://www.linearteam.dk/default.aspx?download=winisdpro
Play around with the different design options and find one that suits you.  If you need help with how to determine this I can try to find the optimal setup for these speakers.
Currently I have a PowerAcoustik Mofo 15 in my Jetta and although it's supposedly a cheap crappy sub designed for poor man's SPL it actually sounds great because of the design of the box.
If you want help on the optimal design please let me know
what type of car you have (year make model)
if you plan on building the box yourself and what box building experience you have
What your box budget is
What your wiring budget it
What your amplifier budget is
Location of box (trunk or if you are ripping out the rear seats and building a wall, etc)
What your preference is for music
What your preference is for sound quality vs volume
If you plan on changing door speakers from factory
Budget for door speakers

Overall max budgets. Etc.
I’d love to help.