QUOTE(Superhawk996 @ Feb 20 2022, 11:55 AM)
Be forewarned, NVH is going to get worse on it's own with just Perlon. The combination of the OEM asphalt mat (mass damper), the fiberboard backpad backers (noise barrier), the contour foam (noise absorber), and the vinyl (noise barrier) is a pretty effective noise treatment.
I'd consider the addition of at least Dynamat (a highly effective, constrained layer + mass damping) behind the Perlon. Dynamat is going to be more effective than the original asphalt mass damping mat was.
Was hot to move to a carpeted firewall a few years ago—they look great!—but never got around to it. Thanks for a reminder of why I shouldn't.
I've actually been thinking about adding insulation under the engine lid and a dual-pane rear window. Even with a factory airbox, a 914-4 engine-side mat, the asphalt mat inside, and a full back pad, the Mezger six is a
lot to listen to when the top is on. When the top is off, it's pure heaven—which has kept me from making any changes so far…