2002 jeep liberty, stereo

ok mayby I did not make this clear.  The kenwood harness has one black (ground) one red (ignition) and one yellow (battery).  The factory harness has two black, two yellow and one red.

Do I hook all 3 blacks together and all 3 yellow together?

trying to complete install tonight can anyone help

I recently replaced the head unit in my 2002 jeep liberty with a kenwood KPC_MP828.  Looking to replace the factory speakers but have some questions.  I currently have 6 speakers  2 in the dash, 2 in front door and 2 in rear door.  I am assuming that the head unit recognizes the front as the dash and front doors and the rear are considered the rear doors?  Is this correct?

I'm assuming that for replacement I would want to go with a component set for the front dash and doors.  I am looking at the following 3 units.  Can anyone make a recommendation between the three:

Infinity 6000cs (90 rms watt, total 270 watts) $99

boston acustic FSC0 (150 rms watt, 300 total) $134

Cerwin Vega VMAG6502 (50 rms, 100 total) $99

Then what to do with the rear doors?  6 1/2 two way, three way or bass driver?

Also considering an amp for speakers.  How many channel would I need and how much power would I need?   Are there any "guidlines" for specifing amps?  What are the differences between amp classes?

thanks

I was inspecting my vehicle for an amp installation (2002 jeep liberty) and found two wiring harness under the driver and passenger seats.  Can anyone tell me what these are for?

Also when I install the amp will I need to run speaker wire from the hu to the amp.  or does that signal come in through the Rca connectors.  Also can the amp be grounded to the seat rail?

I don't know anything about a Jeep Liberty, but I'll take a wild guess about the wiring harnesses: did the vehicle have an available option for power seats and this model does not have them?

As far as the stereo questions, getting a signal from your HU to an amp will use the low-level (RCA) outputs from the head, assuming it is an aftermarket head unit.  If it's the one that came with the vehicle it will likely not have RCA outputs.  In this case you need a speaker level output converter (aka an LOC) to connect to the speaker outputs and send the signal (using RCA cables) to the amp. 

Seat and seatbelt mounting brackets and bolts is generally not a good ground location, as the seats tend to be bolted onto parts that are often isolated or shock mounted from the chassis and they use hardened steel bolts or welded studs which are not the best for conducting electricity.  The best location is to drill a hole through the chassis (through the floor of the vehicle) and scrape off all the paint and use your own bolt with star washer and locking nut.

Ok.  Yes I have 5 volt rca outputs on my hu.  I have a kenwood kdc-mp828.  Looking at replacing the 6 stock speakers and possibly adding an amplifier.  Just not real sure on what to get.  Don't want to spend more than another $250.

I figured I can get a decent componet set or a good pair of 2 ways and at least a 2 channel amp for 250.  Any recomenations?