A sound pressure level (SPL) sub will put out loud bass but it will, in general, be low in sound quality (SQ).

What this amounts to is, it will be loud as hell but it will sound like crap for daily listening. This is a general statement keep in mind. The sound quality and sound pressure level will vary depending on the type of box, amount of power and the vehicle you put it in.

I'm running a DD9515 and I use it for street beating. I've got it setup so it sounds great for daily listening and it is loud (although not at its full potential obviously). For showing off, drawing attention to yourself (not necessarily good attention), and setting off car alarms, it works great. It is possible to run an SPL sub for daily driving. It all boils down to how you like to listen to your music and how well you can setup your system (box tuning, amp settings, etc).

Example: A large box will put out a deeper, boomy-er bass. A smaller box will be tighter bass.

A ported box will be louder than a non-ported box in general. A ported box also requires less power for your subwoofer.

As you can see, many things, including way more then I have mentioned here, affect the SPL/SQ of a stereo.

So pretty much I could have just said "SPL SUBS ARE LOUD. W7 IS NOT SPL BUT IT IS PRETTY LOUD."

 

Anyone know where I can pick up a 13W7 new for a reasonable price? Or 2 10w7s?

 

I tend to find good deals on all things car audio on the site Onlinecarstereo.Com - Wholesale Car Audio/Stereo Deals At Bargain Prices.

13" 2000W Dual 1.5-Ohm Subwoofer $699 USD

You still have to pay duties and shipping on it. So far, I've always come out ahead on anything that I have bought off that site.

Also check with the forum vendors. They seem to have decent deals.