Just finished installing my MTX Thunder 895 5 channel amp. I mounted it to a piece of MDF that was then screwed to the rear wall behind the seat. The ground is also screwed to the rear wall behind the seat. Power wires run in through the firewall on the right side down the door channel to the amp. I ran the RCA's and 4 speaker wires right down the middle under the center console then under the carpet on top of the transmission hump. You can't see or really feel them under there. All in all it was a pretty easy install.

The head unit is a Kenwood Excelon KDC-X689 and I have Alpine Type-S SPS171A (6.5") components in the front and the stockers in the rear. I have a 10" sub on the way which I will build a box for. I am disappointed in the sound quality of the Alpines in the front. They sound kinda flat with out much bottom end. The stock rear speakers sound better in that respect. Any ideas on improving the fronts?

Here is a pic of the install...

 

As far as your Alpines go, make sure you have a sealed inclosure and not leaving space around the speaker and the original 6x8 enclosure opening. Second thing, is the all of the SPS models are not really meant to produce base frequencys very well. The SPR models tend to have more base to their sound. Wait untill you get the sub and cross it over correctly and I think that you will not have as much of an issue. I like the mid and highs of the SPS-571A ' s I have installed in the front of my truck, awaiting my sub amp delivery, so I can really tell what is what. I would hold off on doing anything drastic until you have you sub in and crossed over your Alpines in front so they dont have to produce all that base. They will clean up some when they are limited to high pass sound only and letting your sub do the lower frequency work.