Good shallow-mount sub?

[DFA]

Well, a couple of weeks ago I ditched the stock speakers and replaced them with a set of components in the front and coaxials on my rear doors. HUGE improvement over the crap factory paper speakers, in spite of the fact that I'm running them off my deck's power alone.

Even tho I'm very satisfied with how my sound has improved, the lack of low-end on my setup is starting to tick me off, so I'm looking into getting a sub into my Yaris :)

Thing is, as many of you may know, the trunk is just a bit more over 6sq feet, and, being an engineering student (TONS of books, a toolbox, measuring instruments, misc crap), 21 years old (crates of beer, kegs, beach luggage, etc) and a bunch of other things, I can't afford to give up any of my precious trunk space to a huge sub box. So I'm looking into a shallow-mount that I could place under the trunk's "plastic floor" that will fill in the lows really nicely.

I looked into the infinity basslink thing, but heard it in person and would like something with a bit more punch.

Now, I'm not planning on getting into any audio competitions with this thing, but I'd still like good sound. My first priority is SQ and not SPL.

Looked into the 13TW5 and, in spite of being a mouth-watering sub (and probably the best shallow mount sub atm), I'm not ready to blow $400+ on a sub.

I saw a couple Pioneers at a store (just boxed, for some reason shops in here don't like setting up demos for shallow subs.), a 12" TS-SW3001, and a 10" TS-SW2501 (which is oddly about $30 pricier than the 12"). I thought these were pretty good, but I'm not sure: I've heard/read VERY mixed reviews about Pioneer subs.

But, since probably more than 70% of YW knows more about car audio than I do, I wanted to ask for some advice on the matter, anyone have any thoughts on those 2 woofers, or any suggestions for any other good ones?