Hello,<br /> Use both. You would want to user the sheets for the floor boards and trunk of your car. That alone will eliminate a lot of your road noise. I'd use the spray on the door panels and areas where it's hard to have the sheets stay in place and are very curvy. The floor panels and trunk interior will be ideal to use sheets since they're generally flat and you can lay the shetts firmly in place.
-Jaminlogic<br />Eclipse 8303r<br />Infinity Kappa Components & 3-way<br />MTX Thunder Amps (2)<br />Carver Pre-Amp Processors<br />12" Aura Force<br />Lightning Cap by Rockford Fosgate<br />Wiring by Phoenix Gold<br />Paid $1200.00 for total system.