Sealed or ported box?

Hey folks, first post.  Hello to all.  I do not have any components yet, but I do plan on purchasing a single RF T112d2 sub, and an RF T15002  amp.  I plan on running it @ 4 ohms.   I might go with two T112d4 subs but who knows. I listen to metal, so I am unsure whether to go with a sealed or ported box.  Having a tight sound would be great, but every now and again setting off car alarms would be fun too.  Is there a clear cut line between going for SPL and a tight sound? 

I have been reading up on upgrading the power system, and have read the threads on upgrading "the big three", and replacing the stock alternator with a HO unit.   Got that covered.

I am installing this in a 01 Mazda extended cab pickup with an Alpine CDA 9856 head unit.  

Any help or suggestions would be greatly appreciated, thanks.

Tim

Just so you know what's up with this woofer and why I say it is an SPL driver (and not going to be very good for SQ in my opinion) here's the estimated response curve in the RF recommended enclosure of 2.25 cuft ported at 40Hz.  You can see the big booming spike at about 44Hz and some serious cone excursion issues below about 32Hz.  You will definitely need to use a subsonic filter set to about 35Hz to try and protect this driver.  It looks like a good SPL system, but I would hate living with this kind of response curve.

I had looked on the RF site and could not find that graph anywhere.  Anyhow, that spike(and what you said) makes me think that this sub would not be nice for an everyday driver vehicle unless I listen to bass test CD's all day!  

So then that would lead me to ask what RF (can you tell I'm partial to em?) sub out there has a smoother output across the range, DVC, 500-600w RMS?  I guess there is the P312d2, but I cannot find the graph, so I have no idea what the output curve looks like. 

Well, Rockford doesn't publish graphs like that, I created in using Unibox and the T/S specs they list for the woofer.  I agree with you, this sub looks like a possible SPL comp solution but not for everyday music.

Partial to RF cause I always thought they were the baddest thing around since back in the day(93-94), and most of my friends wherever I happened to be(in the military) always had RF.  I want to run a 500w RMS sub(maybe 2) off of one mono amp @ 4 ohms.  I do not want to work the amp over gettin what I want, which is supporting the bottom end for listening to Slayer, Cannibal Corpse, 6 Feet Under.  Lots of double bass drumming.   I would rather have a larger amp turned down than crank a smaller one.  Thats why I was gonna go with the 15002.  Its rated for 1000w @ 4 ohms.  Budget?  Well, if I could get  one or 2 subs and an amp for $1,000 I would be happy.  If your suggestions are marginally more expensive, then I guess I have to save more money!  I would not mind getting another brand sub, but I am pretty much set on the RF amp.

http://www.videocodezone.com/videos/t/the_black_dahlia_murder/vulgar_picture.html

an example...