Okay so I recently just bought these subs:

http://www.dualav.com/mobileaudio/bp1204.php

I'm looking through and I'm trying to figure out how exactly I want to set these up

My first question is, will I be able to use the factory pioneer amp with these subs? And if so, can I just modify the wiring so I can connect it to the new subs

If I cannot do that, I'll most likely have to buy a new amp. And if I do that, will I be able to mod the wiring to the current sub and split them to make new wires go to the new sub and basically have a set up of 3 subs in the trunk

 

1) cannot run using stock amp, not nearly enough power and if i remember right those subs are 4ohm and our stock sub is 2ohm
2) if on stock head unit need to get a line out converter
3) do not run your stock sub and those at the same time, will sound bad, disconnect your stock sub

 

You will want to use an aftermarket amplifier for the subwoofer. You can still continue to use the stock one for the other 6 speakers though. As Venum said, the stock amp is underpowered and will not push your new subs very well. It barely is enough for the stock one. When I had my G5, the amp I used with the Pioneer stock sub that I purchased hit alot harder than the stock amp in my SS does.

You can sell your stock pioneer sub for a good price. I'd imagine you could easily get 60 out of a pristine condition one.

 

First tip get rid of those subs they are horrible in every shape in form.
Anyways
unless those subs are 2 OHM stable I wouldn't suggest using the stock amp.
It would work it would just make the amp very angry and be dramatically under powering your subs.
I don't drive a SS so I'm not sure what type of amp it has. But seeing as it is a stock amp I'm almost certain in a POS amp

 

What size amp should I get? Or what brand?