http://www.aussiemagna.com/forums/showthread.php?t=91622

Would it be worth putting these into my 380 VRX? I am still learning pretty much everything about car audio. So I'm not sure how these will perform compared to stock system in my car. I don't wanna pay for something if it won't sound that good and I'll end up replacing it. Would rather get it right the first time.
Now keep in mind that I'm not interested in entering any sound competitions, nor am I really interested in changing over the existing speakers in the car, I think they sound amazing for what I need. I'd just like to have a bit more bass.
I mainly listen to hardcore. So lots of doublekicks. No woooob-woooobs or anything like that. Not sure if that will influence my choice of sub as well..

IMO (and I'm not an expert, just the first to reply) Any subwoofer added to most cars will make it sound better, so unless you're ears are quite good (mine are bad) then choice of sub & setup doesn't matter as much as just having one. :)
So if that fits your budget then it will probably add some good sound to your car. Is it the best? No. But then it's not the most expensive either. :)

What head unit do you have? If it's factory, it (probably) won't have a subwoofer output, so you have to work out how to control a sub.
A budget way to do this is to choose an amplifier that has built in crossovers and that can take speaker level inputs and bridge it from the rear speakers. This might have an impact on the rear speakers and possibly even the head unit's amplifier due to the additional load, but I'm not sure how much "load" the amp adds.

IMO, by the sounds of your music taste, you want a sealed box for a subwoofer to provide more accuracy in sound. This means more power would be better.
I've got around 250W RMS running a 12" sub in a sealed box - it's great for listening, not amazing for showing off but that's fine with me.

My wife's car has a factory subwoofer - it's a 4" speaker inside a convoluted ported box and has a built in amplifier about 20W - it's better than nothing and highlights my first point :)

What's wrong with me? :(

I hear ya, the standard speakers are enough for mid-high, but it is missing that boom bass you get from a sub, which I don't believe you will get from that one unless you plan to install it inside the cabin. In the boot, and the size of the 380, it wont be much better than standard.

Just chiming in here, lol at da 'Woobs', I ran a 400 Pioneer Ohms Deep woofer in a sealed box with about 350 watts running at it, it did really well, while I don't think the slim are quite as good as the full depth models, that sub placed in the right sealed box, would suit the music you like, with the advantage of leaving you a lot of boot space.
I'm running a 150 Watt sub/200 Watt Amp combo in my 380, and it's more than adequate, it can pump.
I also rate the clarion amps as good value, its a plus the amp and sub match well, and its got high level ins.
Wether its good value for you, thats up to you, but you could do worse..... And you may have to spend a lot more dough to get substantially better.

Listening to hardcore, which I don't, I'd imagine you just want the punches of the double kick sound pressure in the cab, sealed would suit it.
You'll just have to allow for a Amp wiring kit in the budget.
I'm sittin on the fence with what M4DDOG had to say, It will work in boot, but it needs more power, but what sub doesn't......
I reckon that would go just enough with stock speakers, but not with a fully amped system....I upgraded from from my ol' pioneer, after about 2 years, but I had splits in there too, they got upgraded too.

Don't get me wrong, you'll get a good bass sound, but my experience with these is you don't get the boomy bass. The standard system in a 380 has alright bass sound, but lacks the boom. It's hard to describe lol.

Is it just th is type of woofer you are refering to.
Sealeds have a thump, more than the boom of a port.
They just need more power to pull it off really well.
Hence my 1200 watts at my sealed 600.
If I recall correctly, that sub doesnt like ported box, but I do remember my old sub, shaking the mirror and massaging the seat.
Minding that the OP seems to want mild bass.
And second hand is good way to go, as you'll usually get a lot of your money back.
But I have a problem recommending stuff that will just do the job, there is no room for growth..

IF it's not loud enough in the boot, put it behind the drivers seat :)

My 12" sealed wedge shaped box is behind the passenger seat. Until now, it's been a good foot rest for the 3 year old that sits behind it, but his legs are getting longer and I'm going to have to move it to the boot. I'm not sure if I'll like that. :)

Have decided against buying after the advice here. In saying that, turns out they had been sold anyway :p
Will wait for a bit until I can afford something a bit bigger. I'll probably ask for some more advice at that stage.
Thanks everyone.