We love cars of all shapes and sizes, and we have a firm rule to never ever autobody-shame our fellow car enthusiasts. Real vehicles have curves, and we’ll be the first to admit we like a little junk in our car trunks. Unfortunately, that junk can lead to unwanted noise.

Soundproofing your trunk will go a long way to better car audio, especially with a killer subwoorfer, and it will quiet the unwanted noise like rattles, exhaust noise, and tire noise from leaking into your cabin.

Luckily, the trunk is one of the easier spaces to apply sound deadening and sound blocking material, think of it as Spanx for your car - keeping everything in place and absorbing all the vibration (maybe we should work on our analogies).

Road Noise

Most car trunks sit almost directly above the exhaust and the rear wheels. Since there’s not much of a barrier, the low frequency road noise from these parts of your car easily leaks into your trunk, where the sound bounces around and enters your cabin through the back seat and rear deck. This problem is amplified if you have a hatchback or have modified your exhaust or wheels.

Trunk Noise

Your trunk has a tough job. It houses your spare tire, a jack, roadside kits, tools, groceries, golf clubs, your gym bag, and whatever else you need to haul from A to B. All that rattling and daily cargo can cause quite the ruckus. And although a subwoofer is supposed to upgrade your car audio, your rear deck and trunk area aren’t built to handle that extra vibration (especially not the trunk lid). All of this combines to degrade the listening experience.

You may be surprised to learn that most trunks are between 15 and 30 square feet. Ensure you have the right amount of butyl rubber sound deadening material for your space (never use asphalt!). Trunks are full of nooks and crannies so when dealing with tricky areas we recommend using a sharp utility knife to cut your deadening material down to smaller squares to make it easier to apply. Sound deadener is most effective if it’s fully adhered to your trunk, so apply firmly using a hand roller.

Cover at least 60% of the trunk, walls, rear deck, and lid with sound deadener. Focus coverage on the wheel wells as that’s the source of a lot of vibration. If you have a subwoofer, you should cover 100% of the trunk, including the lid. You may also want to use a decoupling foam, like OverKill Pro™, to prevent the rear deck lid from rattling or bumping your back window. This is because your trunk is subject to much stronger vibrations than it would face from normal rattling and road noise.

INSTALLATION TIPS

If you decide not to cover 100% of the metal surface, put the bulk of the trunk sound deadener on the flatter, flimsier metal sheets. The curved parts of the trunk are more structurally sound and tend to rattle less.

If you're trying to conserve sound dampening material, use the checkerboard approach highlighted in Mark from CarAudioFabrication's video build.

Imagine unwanted noise like a thunderstorm. While sound deadening material only needs to go on some of the structure to keep your house from rattling, the only way to stay dry is to be fully covered from the rain. If you want to keep noise from raining on your parade, apply automotive mass loaded vinyl to the entire floor and walls of your trunk. There are 2 approaches to this.

One of the easier methods is to adhere our Luxury Liner Pro™ to the cardboard shelf or carpet that covers your spare tire, which allows you to remove the material as needed. As long as the trunk is fully covered and the foam side faces down, you will get superior sound blocking.

If you want to be thorough, the best way to keep out road noise is to apply sound blocking material directly over your sound deadening material. Head over to our Luxury Liner Pro™ page to use our coverage calculator tool to determine exactly how much material you'll need. It’s super important that you get FULL coverage and use foil tape to seal any gaps. External noise will leak through any opening it can find.

Note that most cars have a ‘relief vent’ in the trunk. This is a flap that equalizes the pressure when you close your trunk. DO NOT cover the vent! If you do, you may not be able to close your trunk anymore (physics is crazy).

Check out our trunk kits to get all the sound dampening material you need plus a hand roller and quality adhesive to fully soundproof your trunk space.

Our products are made of high-quality, fire-resistant materials with safety in mind. Our mats are 100% high quality butyl (no asphalt!) and are proudly manufactured in the USA.

• Damplifier Pro™ should be installed on at least 60% of the trunk's metal. Focus on the larger, flatter metal spaces. Placing sheets in a checkerboard pattern will help you get the most out of the material.
• Don't forget the lid and the wheel wells! These are two of the noisiest parts of any vehicle.
• Install Luxury Liner Pro™ on top of the sound deadening. Don't forget to leave access to the spare tire!