Spectrum is actaully an undercoating. Many of our customers use Spectrum on top of Damplifier only becuase they do not want to use it under the car like it is intended.
Damplifier inside the car.
Spectrum under the car.
This will sandwich the floor bettween the 2 different vibration dampers.
If you want to start reducing Airbrone noise, use Luxury Liner Pro on top of the Damplifier.
Spectrum on top of Damplifier will help increase the results from the Damplifier, but not nearly as much as some of our competitors might have you think.
The only Time I use Spectrum inside the car, is if I want to hit all the areas I missed with Damplifier Pro. Then it help pick up hard to reach surface area.
ANT