If i where to put a sub in my MK1, it would probably be one or two of these:
http://www.crutchfield.com/S-IL6ckppNEC ... 13-WS.html They don`t require very large boxes, and they don`t need to be ventilated so you save a couple of liters there too.

Expensive, YES, but I had a 15" Focal in my 86 Camry, and to say that it played the hell out of most subs I have ever heard is to put it mildly.

Reached 120dB@20Hz, with only 240W

Estimated peak at 140-145dB at 35-40Hz, and it still did throw a punch that felt like being kicked in the chest.

That sub was the a early version of the Utopia series which i linked too, think it went out of production in 1995, still not seen anything as good.

Of course, the 5" will not be close to that, but i still have great fate in Focal, give it a decent amp and it should be good.

As an alternative, i think the polyglass series from Focal is supposed to be really good.

PS: Take this with a grain of salt, i am a Focal-fan
