So, here's my plan for upgrading the stereo. Actually, it's more of a "repair" than an upgrade because it sucks so bad!

Infinity Kappa 62.5is in the front and rear, running off the deck.
Infinity Basslink in the stock location, run to the battery with spliced speaker feeds from all 4 speakers into it. Factory tweets will be disabled.

QUESTION: I am planning to splice the speaker-lead outs from the head unit back to the basslink, which means I need to know which wires on the harness to tap. Does anyone have the details on the stock (non-Bose) head unit?

One possible option I am considering also is to run only front speakers and use the rear leads for only the basslink. This would give me the advantage of using the fader to balance between the fronts and the sub, but I'd lose the rear fill. Maybe it does't matter...any comments on this?

I'm also thinking that when I do all this, I go ahead and run 2 sets of RCAs and an amp turnon lead (all unused for now) from the deck back to the basslink area. This would give me an easy upgrade path to an amp for the Kappas, if I wanted one later, or a head unit replacement. (I don't want to disassemble the car any more than I have to.)

The kappas will all run with the factory speaker wiring for minimal hassle. I realize that a true audiophile install will run fresh leads, but I'm not up for that.

So...comments or suggestions welcome, especially from people running similar setups.

 

I would highly recommend you upgrade the head unit to an aftermarket one in order to prevent splicing into the speaker leads for the basslink. A friend of mine did something similar with his Honda (stock alpine lol), spliced a fosgate on high level converters into the rear speakers and it sounded absolutely horrible. High level signals will sound terrible no matter what you do, since they are first amplified (by the crappy amp in the stock headunit), then they have to be lowered to a line level (usually through converters, but the basslink most likely does the same thing) and then amplified again; with each step distorting the distortion. Furthermore, splitting the power from the speakers will add another load on the headunit, further decreasing clarity.

Best option: upgrade the headunit to one with a subwoofer out. you could get a headunit like this for $200 or so and have more cleaner power for your infinities. Seems like an awful waste to take a nice speaker like a Kappa and put unclean stock headunit power into it. Note also that power from headunits, especially stock ones, is highly distorted compared to the power from an amplifier.

Second best: splice the basslink into only the rears and save the money by only using the Kappas in the front.

Third: splice basslink into all speakers.