Car Stereos: Speakers & Amp Wiring ?, gmc envoy xl, fiberglass boxes

Question
Hey ED i have 2005 GMC envoy XL, my present stereo goes as follow:
*Kenwood kdc-4028
*Clarion (2 ch bridge for sub 400 watts)
*Mtx DVC 15 (5400) all of that didn't work good end up sending back the sub for service as this one was making weird noise.
and now i decide to go for 1 Boston G5 1244 subwoofer and 2 pair of SX65 and Rockford P600.1 DB and i have to exchange my Clarion or MTX for 4 Channel amp for speakers.i have custom case being built by friend mine that is carpenter and good at fiberglass boxes to fit the dome in the back of my envoy.and my question now is how can i wire all of that by my self as i did spend quit bit of money last summer and this time planning to do it by myself to void expense and wife trouble hope to ear from ya .
Thanks

Answer
Hi Leon.

Thats a nice setup man now is the boston 1244 a dual 4ohm or is it a dual or single 2ohm.

as far as the installation you are gonna have to get a 2gauge power and ground wire and 2 distribution blocks for dual amps, that will accept 2gauge wire. 2 sets of RCA wire one for a 2channel and the other one for a 4channel.
remote wire, fuse holder.

First thing you have to do its to run the battery wire, DO NOT pass the wire through the door, the only reason is because when you close the door it smashes and the protective plastic might tear causing some major damage to the vehicle, we ussually drill a hole on the fire wall and then put a gromet to protect the wire from the sharp edges that the unibit might leave behind.
  Once you have run the power wire all the way to the back run the 2 sets of RCA and remote wire (Do Not run the power wire and the RCAs on the same side that will cause engine noise).
  Get the ground from the chassis i ussually get it from the car's floor just make sure there is no paint where your gonna get the ground from and make sure you are not gonna hit the gas tank or any fuel lines, if you cant find a good metal spot with no paint scrape the paint and using a self tapping screw , screw the ground wire tight to the bare metal(use a ring).
  Now that you have all the wires on the back split the power wire and the ground wire using the distribution blocks. and run one set to each amplifier depending on where you are gonna mount them, the remote wire you can split it on the amplifier you dont have to run 2 wires from the deck to the back.
  Mount the fuse holder as far away from the engine as you can and connect it to the battery Do Not put the fuse yet.
  Perfom a quick inspection make sure all the wires are connected right no wires touching then you can install the fuse.
  Now i was asking you about the subwoofer because you need to have the right impedance (ohm load) going to the amp. else your not gonna get all the juice out of the amp.
  That amp does its power at 2ohm so if you got a dual 4ohm speaker that would be perfect or a single voice coil 2ohm would do it too.

thats all i can think of please let me know if i forgot to mention something or if you have any questions, and let me know the specs on the subwoofer so i can give you the right wiring configuration.

Good Luck!.

Ed.