This is one of the simplest and cheapest modifications you can do to your Jeep. For about $10 or less and about 10 minutes time, you can greatly improve your Wranglers sound system.
Step 1: Remove the Speaker Grate
The speaker grate holds the speaker in place, so be careful when removing it.
Step 2: Stuff the Polyfil
Stuff the polyfil in the whole cavity around the speaker and into the sound bar. You can get a lot in there, and the more the better. The spot in the middle can be tough as you can see in the video, but if you prop it up right it should stay in place.
Step 3: Replace the Speaker
Gently replace the speaker with the polyfil behind it, make sure to line up the screws and not over tighten them when replacing the screen.
Step 4: Repeat the Process
Repeat the process on the other speaker
Step 5: Enjoy Your Upgraded Sound System
The polyfil really makes a difference in directing the sound and reducing the tinny hollow sound of the sound bar. Enjoy!