The Noise **** his name is LSFARM try searching on that instead there are several really good threads with db readings before and after. <br>I did the dynomat xtreme and brown bread stuff to my interior. The extreme is imho a better product than the brownbread but definetly more costly, long story as to why I had both but I used one layer of each wherever I used 2 layers which was most everywhere. For dynomat extreme try going to www.thezeb.com they had the best price far and away from anywhere else I found. Between the both of them I used about 150sf and it was easy to do. I removed the door panels did the inside of the outside skin, the inside of the inside panel and the outside of the inside panel of all four doors. Removed the back seat and carpet and did the back wall and floor with two layers. Removed the front seats and carpet and did the floor and up the firewall as far as possible. I even put some in the cowl area as much as possible that thing is a cave. The biggest gain was doing the back wall and rear floor. The back wall had zero and the rear floor was minimal and zero in places. It definitely reduced the exhaust and road noise. Was it worth it, depends on what you are looking for. It did quiet it down, it was noticeable and it really did take the edge off and make the doors close with a solid thud. Stereo sounds better for sure. Quiet as a lexus it is not. I have not gone here yet but will, the shifter boot for the 4x lever will get some foam as soon as I get around to it.

 

ok, doug gets theoretical again :P<br>some day I'll get a chance (If someone doesn't beat me to it) to test the theory that dynomat and brown bread are not the best choices for the floor/seat pan and firewall. Since both of these products are damping materials, their primary goal is to reduce the vibration of the surface on which they are installed -- by adding mass to it. The surfaces most likely to benefit from such treatment are the door panels and other skins that are flimsy and which vibrate easily.<br><br>Realizing that this theory has not been tested, I suggest that the firewall and seat pan are the surfaces least likely to benefit from a sound damping material, because these panels are going to vibrate anyway even if you do add mass to them. kind of like the valve cover ;D. Anyway I suspect the success of damping materials in these locations is due to the fact the they are, as a secondary effect, operating as a sound barrier material. Perhaps this is why dynamat extreem is more effective than std dynamat-- it may be a better sound absorbing material due to the aluminum layer. Not sure I would put aluminum on the floor, though <br><br>But for the about the same price as dynamat extreme you can get Cascade &quot;VB3&quot; material, which contains a lead layer instead of aluminum, and which reduces (aborbs) sound energy to the tune of 18 dB at 125Hz, and 36 dB at 4 kHz. this seems like an ideal material for the firewall. They make another material &quot;VB4&quot; which is more suitable for the floor (no lead) and is only ~ 3 dB less effective overall, and just as effective (-36 dB) at 4 Khz.<br><br>A sound absorbing material would be great as a cover for the injection system, which itself rattles pretty loud. that and the valve cover and oil pan, like scotty pointed out. BTW scotty, I think you're right about the hood becoming a drum. but a good damping and absorbing treetment under the hood will help two things: (1) the hood itself won't vibrate like a drum and radiate energy to the outside, and (2) the sound absorbing mat will tend to contain the acoustic energy within the engine compartment so they won't travel. If money were no object I'd put a damping sheet like dynamat or cascade VB2 on the underside of the hood, and then cover that with a high temperature absorbing layer like cascade VB-TSXL. But you're right that engine noises within the engine compartment won't just stop at the hood -- they will find their way past the wheel wells and fenders and of course out the bottom. <br><br>as for the rear wall, I still think (as barryg showed) that a damping material would work well, although I would think that an absorbing sheet over the top of a damping sheet would be better yet. that, and eliminate the glass window ;D<br><br>BarryG, can you get under the shifter boot itself? you could put a layer of absorbing material under there. A small amount of that lead-filled VB3 stuff would form nicely to whatever shape it needed to be, and probably be more effective than just foam.

 

Exhaust noise some call drone.... In the '50s we called them &quot;echo&quot; cans. On 1 3/4 pipes we added ford driveshaft extentions, yep loud. Then came muffler laws :'( That is exactly how the Dodge system is built. Cut the oversized tip off and go back at 3&quot;, gets real quiet inside, still loud outside. Mine almost sounds stock inside. No drone what so ever. You hae to listen close to hear the exhaust or open the windows to hear it. Straight piped 3&quot;.<br><br>Now I'm not that smart, just found this out by accident. Have tried several different combinations on the tailpipe, and not oversized tip, no noise. I cut mine at the last bend, added a 18&quot; extention, it routes exhaust at a 45 degree angle at the rear corner.

 

just for grins, I made some SPL measurements on my truck, which is stock except for the EZ box. All measurements C-weighted, expressed in dB, and performed with with Radio Shack digital meter:<br><br>Idle, both windows down:<br>driver: 83 <br>passenger: 81 <br>rear seat: 85 <br><br>Idle, both windows up:<br>driver: 75. moves to 84 at 1500 / 40 mph<br>passenger: 75. moves to 83 at 1500 / 40 mph<br>rear: 78. moves to 80 at 1500 / 40 mph<br><br>Outside @ idle:<br>1 ft Front of radiator: 90 <br>inspecting the trac bar: 100 <br><br>Hard acceleration:<br>driver sees 90 dB<br><br>for reference purposes, 90 dB is about the level of a loud orchestra, and is the limit for prolonged exposure (8 hrs/day) before hearing damage occurs, according to OSHA. 100 dB can be sustained for 2 hours per day.

 

Doug:<br>I agree with your theory. Dynomat and the like types obviously will help some but at what effectiveness/value vs $$. If you are serious about deadening the sound the other type products you mention would be the way to go. In fact when I was investigating the idea I ran across that stuff and it sounded like the best from the research I did. We have to remember we are riding in a vehicle that is nothing much more than a tin can with glass galore right behind a 100+db noisemaker it just wasn't designed to be that quiet and trying to fix that after the fact is difficult/expensive at best. I also agree that if you really want to do it you need to do in the cab and outside the cab(ie engine compartment) and quite possibly underneath. I found I was only willing to spend so much on it. I just wanted to take the edge off (and I just happen to fall into a deal on some at an outrageously good price I actually got all of my brownbread and dynomat extreme for $1.00sf). And not that I wouldn't be willing to do it if I had the funds to burn but when you are talking $3-5sf (I think) and needing a couple hundred sf to do it right that adds up. <br><br>I haven't got around to even checking out the shifter boot yet. It didn't even enter my mind until I was just finishing putting everything back together. It was an after thought sort of a oh duh why didn't I do that when I had everything apart. A hole in the floor can't be good for sound. You're right foam would not be that great but it needs to close the hole as much as possible yet not cause any binding of the shifter. Maybe a piece of that stuff with a slit in it or something. Will let you know what I decide on after I get around to taking it apart again.<br><br>By the way keep up the theorizing (is that even a word) it is good for the brain and helps all of us out .