I really wish this wasn't the case, but from my experience, it's basically impossible to quiet the drone of a loud exhaust with sound deadening. My hunch is there is just too much sound energy there and too many transmission paths into the cockpit. I tried quite a few things to run a louder exhaust, including lots of heavy sound barrier lining areas of the cockpit, and a shield to deflect noise rearward at the source.I am eager to get the 3500 rpm drone eliminated -
Zuspiel, for once again thank you for your instructions!I got 40 sq ft of damplifier but used less than half so far. I got more since we had already planned on doing my boss'es undertray and I have other things planned...
2 "sheets" of luxury liner pro ( 18 sq ft). Those are mostly gone. You definitively need more than one to do everything I did. I wasted a bit since I was a bit dyslexic on cutting two pieces (cut the mirror image...)
Also, make sure you have a roller and the right glue if you decide to glue the LL. Second Skin sells those, too.
The damplifier is adhesive backed, so that always gets stuck on. It needs to have a good bond to work (use a wooden or rubber roller). It can be removed (once ) by peeling it off. I glued the Luxury liner to the damplifier with spray contact adhesive. From psoup's experience, that's not strictly necessary, but, as a friend remarked a while back, I'm an "anal little prick"
It also helps stiffen up the floor. I was surprised how much sturdier the floorpan felt after gluing the LL to the damplifier. I don't think you can remove the LL from the damplifier once glued since it's glued foam side down. But the whole sandwich should be removable (and will be trash once removed...)
Thanks once again, you guys rule!!John, the damplifier is basically butyl rubber with aluminum on one side. The butyl rubber side is basically a sticky tar like substance. You want the roller, because it is more effective the better the contact with the underlying surface you have, and there is a tendency for air to get trapped which prevents contact. Start on one edge, and then slide your finger back and forth from side to side as you apply it, then use the roller to make try and get as much contact as possible.
You want to remove the plastic trim first, then place the damplifier and LLP directly on the fiberglass, the LLP was glued in place over the damplifier. If I had a free edge with just foam, I cut some of the vinyl from the foam and faced the edge with the vinyl (see pic #3). Then I put gaffers tape on all joints and seams to hold them together nice and tight.
I am in the process of doing this, it takes a lot of time to get it all fit in just right, started yesterday, spent about 4 hours, probably about 4 more to go. Basically I tried to cover every square inch with LLP.
See pics, I'll post more when I get it all done. The little squares right on the firewall are the damplifier, the mat is the LLP.
Don't use Damplifier which is for resonance suppression of metal panels. You want to use a foam liner like overkill foam or DYNALINER, this will provide sound isolation and knock out rattle and vibration, plus it's much lighter. I recommend using a self adhesive one, the overkill is a great product but the adhesive is a pita to work with. See picture 8 posts or so above, like how I treated the firewall trim piece is what you should do for the dash.Anyone try to put some damplifier under the dash? Mine rattles/vibrates some, but I'm not sure if its making much noise, other than the rattles