They're SPL components. Looks like aluminium drivers.
Got them really cheap so I've got nothing to lose by putting them in - they can't be any worse than the VW OEM stuff
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I'd thought the same thing about audio wave transference between surfaces (I'm a pro Sound Engineer by trade
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). Will be interested to see how they sound.
I'm treating this more as an experiment to see what can actually be done - going to document it at the same time and put it in my Project build
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Also got a load of acoustic foam and Dynamat to install too - busy weekend!!
Dan