I have the I-Sport AT (non Bose) system. I wanted to upgrade it but retain the stock head unit. In the process I wanted to install some mat for sound proofing as the 6 has quite a bit of noise, mainly wind and road.
Amps are the 4 ch. Precision-Power-PPI-P900.4
Precision Power PPI P900.4 Phantom 4-Channel Amplifier
And a mono Alpine MRP-M350 from my last car.
Rear speakers: Precision Power PP-A2.65C. These are unique since you can run them as coax or separates. I opted for co-ax initially as I didn't want to mess up the front sound stage too much but I may try the tweeters higher later. Used the Audio Control LC7I which uses the stock speaker leads and splits into front, rear and sub RCA outputs. Slick unit with individual level controls for all 3 and adjustable accu-bass which contours the low freq. roll off. This is mounted above the glove box. Easy to adjust as the GB comes out in 10 seconds with no tools. I did have to trim the to corner right side wall of the GB.
Stock rear speaker:
MDF wood rings for speaker mounts over sound mat. I used the excess trimmings inside the panel behind the speaker. While driving with the inner panel off I found the thin plastic hole cover in the upper left allows a surprising amount of road noise in before covering it. There was room to mount the cross over under the inner panel above and right of the speaker.
Front Speakers: Precision Power PPI P.65C3 3 way front speakers, mids in the tweeter dash location and AMT tweeters on the A pillars.
They honestly do sound this good:
PASMAG | PERFORMANCE AUTO AND SOUND - Precision Power P.65C3 Component Speaker Review
The front doors have quite a bit of insulation in the inner panel, the rear doors had none. You can't flush mount in the front even with MDF rings as the sliding door guide comes in right behind the speaker when you close the door. I gutted the stockers and screwed through the plastic enclosure into a MDF ring. Crossovers go up behind the kick panels on each side (front).
Midrange's in the stock tweeter location:
The AMT ribbon tweeters go high in the A pillars:
I also matted the A - B and C pillars as there is nothing under the plastic trim but sheet metal and holes to the outer skin. Of course taking care around the air curtain bags in the A & C pillars. I was started by doing one side and had to drive the car, I could tell the difference as the non-matted side was louder.
I used some good 6 gages pure copper power leads to the trunk:
Mounted the two amps to a covered board. I used rubber hose for spacers over the trunk springs for a bit of vibe / road isolation. Also installed a SPST switch for the sub amp remote on lead in case I need the space and pull the sub. The small white spacers help keep the amps cool allowing air circulation all around.
I kept it small and simple with a JBL GTO 1014 - 10" in a sealed box.
All said the car was good to work with. The large holes where the seat release cables come into the trunk are fantastic for routing / stashing excess RCA's and wiring.
Most of the work was the sound proofing and a bit of splicing where the harness adapters did not have leads for the stock unit. The only alterations were some trimming of the sill plates underneath to make room for the power cables and RCA's and a bit on the glove box corner. None of which are visible. I wanted to have this done before winter and just started it when in I broke my collar bone mountain biking late fall.
Yes, I could have gone after market on the head unit but I wanted to retain the camera, steering wheel controls and stock USB / Aux. locations.
The Blue tooth works fine with my phone too. Im actually very impressed with how well this set up sounds. I need to do some more tuning but so far it's clean, LOUD and has enough tight bass.