Installing 9-5 door speakers into the C900
This is step that will make the install either look like crap or very professional.
You do not want to cut out more door material than necessary.
Getting the hole the right size will take many small trial and error cuts.
In my case I got impatient and went crazy. If you are tired from the previous two steps, I would suggest to take a long break and come back fresh.
To start, I just had someone hold the panel close to the right position and I used a marker to mark the inside of the door panel. I then used a dremel with a sideways cutting drill bit.
This tool is tough to use because it can go wild with little to no warning. The best thing to use would be a foam cutting heating element, but I'm not sure where to but this from.
You will make a big mess no matter what tool you use!
Once you get the hole the right size you should end up with something like this.
As you can see, my hole could have been better! You can do better!
My last recommendation is to make sure your are not sending high frequencies to the door speakers.
You should only be sending mid to low range. Since the speaker is mounted sideways, the high frequencies will distort the imaging and make it sound like the singers are at your feet!
Your amplifier should have a setting for low-pass and then have an adjustable frequency range. You want to set it as high as possible.
If your amp does not have this, then you can buy an inline low-pass crossover from tweeter.com.