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Discussion Starter #1
2 step solution to quiet down the STI:

1. get rid of the school bus sounding RE070's

2. I spent about $100 bucks and bought a few cans of dynamat spray and a few rolls of dynamat extreme. Pop off the door panels, carefully peel back the plastic and spray about 2/3 can of the dynamat up into the inside of the door (do all 4 doors). Don't worry about being picasso ! Then, unbolt the seats and peel up the carpet and put a roll of the dynamat onto the floor (1 roll should be sufficient for each side). Cut the stuff into manageable strips and be careful because the aluminum backing is as sharp as a razor. I used the back end of a screwdriver to get out the air pockets and to make it conform to the floorpan. I didn't disconnect the airbag plug for the seat either, and I don't recommend it because I have no idea if that will cause "bad things" to happen when you plug it back in. And in case you wondering, the weight gain is very minimal...It's worth it for the gains in cabin comfort. Don't expect it to be as quiet as a Lexus, but it's a great improvement.
 

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That's very interesting information Hellrocket. I'm sure there are many of of us that have thought of the same thing. I have considered the sound deadening material, but for the reason of weight constraints, have shy'd away from any serious thought of installation. How much would you guesstimate the added weight to be..doesn't have to be specific. Again, thanks for the detailed info.....
 

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I will eventually replace my RE070s cuz they'll wear out.. but I'm not sure what I'll replace them with... as it's hard to judge what's out there that performs better. I care about the performance more than the noise.
 

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Discussion Starter #4
I used 3 cans and 2 rolls. a lb per can+1.5 lb/roll....6 lbs ? I think that's rather insignificant, considering that 99% of us put in a head unit and speakers.......Which reminds me that I specifically decided not to put my 12's in this car (2 eclipse aluminum DVC 12's...30+ lbs each) for weight reasons. I have a ton of stereo equip i'm willing to part with, if anyone's interested. Phoenix gold/ Mmats amps, fosgate symmetry, 1 farad cap, diamond/mb quart mids/kicker tweeters....?? I'm a good feedback member on ebay (same name) so don't worry about getting hung out to dry.
Enough propaganda....sorry.
I tried the airbox mod today (removing the resonator) and I wasn't very impressed with the sound. It wasn't the "whoosh" I was expecting, more of a metallic sound, rather than a pneumatic one???WTF?
 

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yeah, i just did the resonator-ectomy and was expecting a little more noise, kind of like the evo, but it's still better than it was. the dynamat sounds like a great way to go. i think that may be my monday project. where did you get the stuff, i imagine a good car stereo place, or can i get it a good-guys or someplace like that?
 

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Question for any who would consider themselves a sound deadening guru.....should you do areas such as that under the back seat? You basically have that big foam pad and then body right there. Is the foam doing a good enough job there or would matting the under-seat area be beneficial. I don't want to waste that much of stuff on an area and not get a good gain out of it.
 

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Discussion Starter #7
Basically, the concept of sound-deadening is adding mass to body panels, etc in order to reduce resonance. Road noise is transmitted quite well through metal, causing it to vibrate....which causes noise. The foam contained in the back seat will absorb alot of this sound, but by adding sound deadener to the body panels themselves, the noise is reduced even more. If weight was not a concern, the best you could accomplish (realistically) would be to remove all the seats, carpet and that felt firewall liner. At this point you would coverany and all exposed areas with 1 or even 2 layers of sound deadener. if you're really hardcore, they make lead impregnated stuff that REALLY does the job well. It;s all about priorities and the law of diminishing returns. It's not too difficult to get a 3db drop in road noise (which would cut it in half), but to get another 3db drop would require much more effort...etc etc. I personally haven't applied dynamat to my floorpan under my back seat, but I don't think you'd get nearly the gain as you would by doing the front floorpans or the firewall. If I had my back seat out for some reason, Id probably do it, as 1lb of increased weight would be insignificant for my application (I don't use my car on a track). On a side note.....every decibel of road noise you decrease effectively adds that much back to your audio system. Hope this helps !
 

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My experience is that the number one improvement will come from doing your door panels throughly, after that I would look at the floor pan under the passenger seats. The roof is only needed if it rains alot where you are, as it gets rid of the "driving in a tin can" feeling in the rain.

You can usually find good deals on Dynamat on Ebay.
 

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I think the doors will make the most improvement. I dynamatted my trunk first, that worked well. Then I covered the entire floor, under seat, over the tunnel, not as dramatic of an improvement. My doors are next.


Go ahead and unplug the seats...nothin' happens.
 

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I used b-quiet in my Integra. It worked great on the door panels. I have one door lined with a layer of B-Quiet® Extreme and nothing in the other and the difference is very noticeable. But what I learned in doing this is that the [tar like] material such dynamat and b-quiet does not block out sound, such as road noise, but rather it deadens vibrations, such as rattles. In order to get that Lexus/Mercedes silent interior you are going to have to add something like acoustical foam or something similar that actually absorbs sound. For example, companies such as Mercedes use a 3M product called Thinsulate Acoustic Insulation to keep their cars quiet on the inside. Unfortunately, Thinsulate is not available to the everyday consumer. But if any of you have some contact with a body shop you might be able to pick some of this stuff up. It is very light weight and is supposed to have tremendous sound absorption qualities.

If you are interest in reading up on this product here are some links.


http://products3.3m.com/catalog/us/en001/safety/thinsulate/node_9C0X0T3W56ge/root_GST1T4S9TCgv/vroot_9C0X0T3W56ge/theme_us_thinsulate_3_0/command_AbcPageHandler/output_html

http://www.3m.com/us/auto_marine_aero/automotive_oem/interior_pages/thinsulate.jhtml

http://www.b-quiet.com/

STi Install --> http://www.b-quiet.com/sti.html
 

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Got a link as to where to buy the spray... photos of it installed in your door maybe? Also, dynamat the trunk or use the spray on the trunk? :D

Signed,
Outferno
 

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I've been using the Fat Mat ordered from ebay during my system install. 3 of the 4 doors done now, with the remainder for the trunk and rear seat.

Hard to hear a difference with the back seat still out....damn it's loud back there!!!
 

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Newbie question: The plastic liner on the door interior. After putting on Dynamat, do you tape the plastic back over it? What do you use to secure it? Electrical tape?
 

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So how did the canned stuff work out?? I just got a bulk pack of the dynamat xtreme and was gonna just do the outer and inner doors, just waiting for it to get warmer here. But I was thinking of using the canned stuff inside the wheelwells underneath the fender liner. Haven't taken a look under there yet but getting rid of some of the road noise would be good.
 

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I have heard that roofing tar paper can work exactly like dynamat. A guy I work with has a friend who works at a sound installation shop and said he uses regular roofing paper in his own car since you can get a huge roll for like 10 bucks, anyone ever tried this or know if it works? Or do you think it would make the car smell of tar paper?
 

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Any STi with a MRO Front Air Dam MY03-04

Tar paper isn't sticky. There might be some other roll roofing material he's using.
 

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The name I keep hearing for el-cheapo sound deadening is

"Peel-N-Seal"

http://www.paceproducts.com/peel-n-seal.htm

I've never seen it, never used it, and the guy at Home Depot didn't know about it.

FWIW. I'd stick to the aluminum-backed stuff at 0.4 lbs/Sq. Ft. over the classic Dynamat-style at about 1 lb/Sq. Ft. There's a persistent rumor that all the 'brands' are purchased from a single [ / small number of ] company, so generic is every bit as good as expensive names.

Rick
 
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