The complete exhaust mod on my 2002 X-Type 3.0 rewarded with much more flow, power, but booming interior noise. As a remedy, I placed a glasspack muffler/resonator before the twin Dynomax Super Turbos (fiberglass insulated twin baffles) in place of the Magnaflows (straight through design). This helped but it is still a little too loud in the cabin. Will placing Dynamat in the boot (trunk) significantly tone down the interior noise generated by the mufflers? If yes, place it where, how much to use, and thickness?

 

You need insulation. Dynamat was designed to deaden sound vibration. Without the invention of Dynamat all the HIP HOP cars would sound like soup cans with rocks in them.

If you want to add insulation look first where it is not. The sound from the trunk is probably coming directly thru the rear deck lid on the interior of the car under the back window. I seriuosly doubt there is any insulation there at all. The rear seat back and seat bottom is the only sound absorbing buffer between the trunk and cabin interior.

Pillows are an easy way to see if it is worth going further. Just cram a few pillows between the back window and deck lid, and listen to the difference. If there is a difference then you can proceed to the next step what do I replace the pillows with? Go to Bed Bath and Beyond and get a foam waffle pad for bedding. The waffle will give you a tremendous amount of surface area for the sound to terminate. Use the waffle pad in the trunk. Test with pillows on the inside of the car.

The next problem is how to fasten the stuff in place. You can figure this out. Get creative.