Stereo set up ideas?

In general, it sounds like you are OK except for one thing: your amps and speakers should be hooked up with Pos (+) on the amp to Pos (+) on the speaker, and Neg (-) to Neg (-).  It sounds like you have everything hooked up in stereo?  If you like the way it sounds, then you are done!

The way you put it, it sounds like you have a bandpass box.  Are the subs completely enclosed, or is one side of them touching free air?  This would be a ported enclosure.  I see best results out of a sealed enclosure, with it being smaller, and the frequency response across a broader plane.  Resistance (ohms) is how restricted a given circuit is.  Take plumbing for example.  You have two different size pipes with water being pumped through them at the same speed.  The bigger pipe is going to allow a larger amount of water molecules to pass through it than the same speed as compared to the smaller pipe.  Same goes for electronics.  That is why good installers stress the need for a large power wire (pipe).  The bigger it is, the more electrons are able to pass through it at the same speed (volts).  If you have different levels of resistance, you can cook something, as it will be trying to push a load too big for the "pipe" that it is trying to go through.  You can cook an amp and even possibly voice coils.  Look at the blue column on the left.  Go to the top.  Under basics click on Ohm's law, that might be able to explain it better than I can.  My own ramblings make sense to me.  LOL

Bridging combines power rails from two different channels, essentially doubling your power output.  You have to make sure your amp is bridgeable (killed that spelling).  If it didn't come with a manual, or it is not marked on the output channels where to place the speaker wire, look up the manual on the pioneer website for that model.  Usually to bridge, you take the two different channel that are closest to each other.  Run pos from speaker wire to the farthest outside pos when you are looking at it.  Same for neg.  Take neg from speakers and run it to the farthest outside neg when you look at it.  The two in the middle are not used.  It will look something like this ( x's are terminals not used)   + x x -     or - x x +        (i can't remember off hand which way they go   :)   )   If you have a four channel amp, great!  You can reach maximum power output with that by bridging two sets ( bridge two together to have one, and the other two to have a total of two outputs)   looking like this  + x x -    + x x -        You can now hook up each sub to its own bridged channel.  They are going to be power hungry beasts.  Like I said, check resistance and specs on the subs and amp.  If your subs are 4 ohm single voice coil (most likely), make sure when you put it on a bridged channel, that the channel is going to be 4 OHM STABLE.  This means that it is rated to run like this, and will not harm it.  I have bridged amps of my own that were not rated to be, you just have to be careful and keep an eye on them, make sure nothing overheats.  I was using the older style rockford, which is a tank if you ask me. 

Well, I hope I solved your questions, if you have any more, just let me know.  Peace bro.

Werd

I think you do have a bandpass box.  I think you should ditch this and get a sealed one.  You will notice a considerable increase in your bass response. 

About the RCA thing.  this amp was designed to also have two different inputs for dual sets of channels ( front and rear ).  What you need to do since you have subs, is get RCA Y splitters, and just split the signal into the two sets of RCA inputs on the amp.  Either that, or if your amp has a set of RCA preamp outputs, just run a short set of RCA's from that to the other input.  I don't think getting a bigger alternator is a big deal, unless you experience power loss, like dimming headlights, or your bass is really good when you first start it up, but over a period of time of playing, it starts to get quiet or muddy sounding.  The first thing I would do is upgrade the grounding wire from the battery to the vehicle chassis.  This is a commonly overlooked thing.  Go with the same gauge wire as your power wire, or bigger.  It also would'nt hurt to upgrade power wire from alt to bat, and so on.  I don't think an extra bat would be any big difference.  This is mostly for people with show vehicles that play the system for an extended period of time with the engine off.  For the ground, you could just run both 8 gauge to a distro block, then have a 4 ga come out into ground, OR you can have 8 ga come from each amp, and ground AT THE SAME SPOT.  This is important to eliminate grounding loops.  For the crossover, I think you should invest in a power distrobution block.  It makes things a lot cleaner, and gives it a show look.  You can hook the crossover in there.  It might be a bad idea to hook it into the amp power channel, cause if you have (should) a fuse inline with the power wire for the amp, it will probably prematurely blow the fuse, as it will be trying to draw more amperage during deep bass notes than the fuse is rated for. 

Hope I helped!!