How to Upgrade Porsche 996 Dash Speaker Kit
Upgrading the dash speakers in a 996, 911 or a 986 Boxster can be a simple straight forward event if you know what you are getting into and have the right gear.
First Thing to Know
The factory Porsche speakers are mounted to the bottom side of the grill and use a proprietary mounting system that will not allow an aftermarket speaker to mount to the grill without either a lot of fabrication, cutting or hacking.
The Fix
Here at Car Audio Innovations we have made a speaker mounting installation kit that we have used for hundreds of installations at our shop. You can order the same kit from our website with Audison or Focal speakers or you can order just the hardware. The job can be done without this kit. The kit just makes life a little easier and your installation much cleaner.
The kit consists of
1. Machined Speaker Mounting Rings
2. Special Mounting Hardware, Allen Wrench, & Drill Bit
3. Speaker Mounting Glue
We have kits for 4" component, 4" coax, 3" component and the kits work for both front and rear speakers on 911s.
Let's Get Started!
Remove the grill and speaker assembly from the dash by removing the two Torx fasteners from the top of the grill and then prying the grill up from the small end. The large end is held in by a retaining clip (see the picture above).Now that the speaker and grill is out, unscrew the midrange speaker and reassemble the retaining clip back onto the grill without the speaker (the clip on the large side of the speaker grill).
Next pry the factory tweeter out of the grill. Use diagonal cutters to cut the factory tweeter mount down to a flat surface.
Glue the tweeter grill (not the tweeter itself) to the factory Porsche speaker grill. Use two small dabs of glue to secure the tweeter to the tweeter grill. Now the tweeter is easily removable for service in the future.
Now the Midrange
If you ordered our Focal kit it will come with a 100KS 4" midrange that has had the four mounting tabs machined off of it. If you are using your own 4" speaker you will have to grind or cut these tabs off yourself. Note: make sure that you don't get any metal shavings into the voice coil of the speaker or it will be ruined!
The speaker mounting hardware kit is also available for 3" speakers. With a 3" speaker you will not need to modify the speaker. No cutting required. 
Before you permanently mount your mid range speakers in the adapter rings; insert the adapter ring into your factory grill and drill pilot holes for the supplied mounting screws through the factory grill and into the adapter ring. Do this first so that you don't risk drilling into the speaker. Orient the ring so that the small side is facing the speaker grill. The speaker is pressed into the larger side and then glued in place. Mounting the Speaker and Ring into the Factory Grill
The speaker ring kit comes with some tiny Allen head screws, and Allen wrench, and the proper size drill bit. Insert the speaker assembly.
Above: Here you can see the 3" version of this speaker adapter.
Use the supplied drill bit to drill four holes around the edge of the mounting surface. Then use the supplied Allen screws to fasten the speaker adapter in place. 
The glue that we include in the kit will make a permanent bond to both the speaker frame as well as the mounting ring as well as your fingers. So be careful. If you purchased the speakers from us then the mid range will already be glued into the ring for you. Take care not to drill into the actual speaker when drilling pilot holes for the mounting screws.
Now that the speakers are mounted its time to wire them up. If you purchased the speakers with the kit then this has already been done for you.
Speaker polarity
Looking at the factory speaker connector in the dash, the side of the connector that has a retaining clip on it is the positive side. The wire with a brown stripe is the negative wire.
If you purchased the Focal component set, you will need to mount the passive crossovers under the dash. The crossovers can be zip tied in place. On the passenger side it can fit through the speaker opening and toward the middle of the dash. Securing it is ideal to avoid rattles On the driver side we usually mount the crossover network to a harness from under the dash, and feed the speaker wires up through the speaker opening. (removing the heater duct along the bottom of the dash makes things easier to see and access sometimes) Try to avoid mounting the crossover to high current cables. The inductor coils can act like antennas for radiated electrical noise. If you end up with a buzzing sound in your speakers even with the radio off, it is because your crossover is mounted in to close to an electrically noisy item. Simply try mounting it in another location. This is rarely a problem but can happen.
Crank it up and enjoy!
I hope this helps some people have an easier time installing their speakers.