There are two complete kits...
There are two complete kits from Shelby Performance Parts. The non-Shaker-based kit is PN KA-NOSHAKER-KIT and retails for $1,249.99. It includes four 6x8 two-way speakers, a four-channel amp, and a 10-inch sub enclosure with all wiring. The Shaker 500/1000-based kit, PN KA-SHAKER-KIT adds the two 8-inch door subs to the mix and will set you back $1,399.99.
Tech | Audio Upgrade
If you look back at Carroll Shelby's history it has always been about improving the performance of a vehicle. From more horsepower to better handling and braking, Shelby has always demanded more from the cars he built and it's no different with today's Shelby products (GT500, Shelby GT, et al). But one thing that is different is today's buyers. Back in the '60s and Ford's Total Performance era (as well as the general muscle car wars of the time) meant power, and lots of it. Today, however, owners of Shelby automobiles want their power with 100 percent perfect driveability, ice cold A/C, and all the power accoutrements, including a sizzling audio system. That last entry has been "Shelbyized" as well now thanks to a partnership with Stillwater Designs, better known as Kicker Audio. Together they have designed the new Shelby Kicker Sound System.
Kicker, like many of the larger car audio companies, has an OEM division which works with car manufacturers to offer its products as an option or dealer-level upgrade. Shelby Automobiles partnered with Kicker's OEM division to make a truly plug-and-play (I know, I hate that phrase too, but it really does describe this audio system) audio upgrade for the '05-'09 Mustang. Kicker developed a package that replaces all of the Mustang's 6x8-inch speakers with high-quality Kicker two-way direct-fit units, a 46-watt per channel four-channel amp, and for Shaker-based systems it replaces the door-mounted 8-inch subs with Kicker versions as well. The two systems are rounded out with a 200-watt amplified 10-inch sub in the trunk (sorry convertible owners, but it won't fit your limited trunk space), upgrading the Shaker 500 system, and replacing the trunk subs in the Shaker 1000 system. Best of all, while these two systems were designed to work exclusively in the Mustang as a package, you can indeed upgrade your Mustang with any of the kit's components separately. Already upgraded your 6x8s in the door and deck but want a sub? You can purchase the 10-inch sub, which includes the built in amp and all wiring all by itself. So check out our install of the Shaker-based kit on our '08 GT with a Shaker 500 system and take a look at the Shelby Performance Parts website to see all of the individual audio gear as well.

A quick comparison of the...

A quick comparison of the OE Ford door speaker and the new Kicker replacement show a vast quality improvement on all fronts.

From a larger magnet, to higher...

From a larger magnet, to higher quality cone and surround material, the Kicker speaker is a huge step up in sound reproduction. The speakers utilize a poly cone with a 20mm Titanium dome tweeter with a 12db crossover.

With the panel free from the...

With the panel free from the door shell you can lean it toward you to access the inside door handle mechanism. The Kicker instructions state to remove the handle assembly and pass it through the door panel, but we simply compressed the clips holding the cable to the door panel and freed the cable from the handle.

The factory 6x8 door speaker...

The factory 6x8 door speaker is secured via T20 Torx screws. Remove the four screws retaining the speaker to the door and then disconnect the modular wiring plug from the speaker for removal.

Designed by Kicker's OEM division,...

Designed by Kicker's OEM division, the replacement speakers have the exact same modular wiring plug for a simple plug-in installation. Mount the speakers using the factory mounting hardware and you're done with the front door speakers.

If your Mustang has the optional...

If your Mustang has the optional Shaker system, the door panels themselves have an 8-inch subwoofer mounted in them. They are secured by a 10mm bolt on the rear of the speaker frame (through the door panel itself).

From the front of the door...

From the front of the door panel, remove the sub's trim ring, which is simply secured via friction clips, and then remove the eight 7mm mounting screws. The wiring for the dual voice coil sub is soldered to the terminals and will need to be cut from the sub for reuse with the new Kicker replacement sub. Cut the wiring approximately 2 inches from the sub's terminals.

Before the new sub can be...

Before the new sub can be installed in the door panel you will have to prep the door panel accordingly and add the sub wiring to the new Kicker sub. First, we tackled the door panel mods. You will need to cut off the two factory sub locating pins, as these will interfere with the new sub's mounting rings. Once the pins are removed install the foam gasket to the Kicker-supplied spacer ring and mount the ring to the door panel using the original 7mm screws.

With wiring complete, the...

With wiring complete, the harness can be routed back through the door panel (ensure the rubber grommet is sealed properly) and the new Kicker sub can be mounted to the adapter ring previously installed, using the new hardware supplied in the kit. A new rear mounting bolt is supplied the for the sub as well.

For the wiring you will only...

For the wiring you will only be using one "side" of the original dual voice coil wiring harness. The two white wires with gray and black stripes (respectively) will require their insulation to be stripped back and installed under the spring loaded terminals of the Kicker sub-gray stripe to the red terminal and black stripe to the black terminal. The remaining two wires should be sealed/taped up to prevent any shorting of the amplifier.