this is a paste from my previous answer.
they say some bass power is robbed just from the energy used to vibrate the metal so it is worth it, there are less expensive materials out there like cascade or other mineral based sheets, and i have found material that seemed good for a dollar a foot for doing extra areas.
sealing the trunk helps also, i use spray foam insulation on seams prior to deadening sheets, u spray a small bead in seems let set for around 10 minutes and using your fingers press out the air.
What u get is a strong seam that is sealed, this stuff is sticky so u want to use gloves, u just let it set up enough to not be wet but still mold able.
after dynamat i have used rubberized under coater if u can let it dry long enough.
This method is great for doors also.
a heavy foam rubber pad on the trunks floor helps and there are some designed for car audio at 2 dollars a foot.
email me i have other ideas
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