How good does the sound deadening products out on the market really work? Is it really worth the cost? Like if you have a system and everything rattles will all of that stop with proper placement of sound deadening material? And where exactly should i put it to stop all the rattles?

 

place it everywhere, inside the doors, trunk, roof, etc

it does add quite a bit of weight , I'm trying to find out how much at the moment, but it's dense material

dynomat, edead, brown bread, etc

 

Its not that much really. I did 3 layers of fatmat over the entire interior and trunk and I didnt add much more than 100lbs. I will be the first to admit I went way overkill too. In a accord your definitely not going to notice a extra 100lbs, especially when its spread out over the entire car.

 

but how were the results?

 

It was like night and day. About as close to a lexus quiet ride as your going to get in a Honda. If I had to do it over again though I would go with Second Skin's Damplifier over the fat mat. Still reasonably priced but more comparable to dynamat.

And if your on a budget and cant afford to do the entire car at once definitely do the doors first, it makes the biggest difference.

 

it's a dense / high viscosity material that absorbs vibration
namely tar

there are 2 things happening when you put in the sound deadening material
one being the most obvious, physically blocks the sound from coming in

the other one is that it dampens the vibration, this works well if your car's a bit old and the factory dampening pad has worn/harden, and your car makes a howling wind noise when you drive.
A good cheap way for this without adding too much weight would be cutting a small patch of the sound deadening material, start tapping lightly on your car's body, and then apply to the part that makes the most "empty barrel" noise.

of course if you want the quality of a luxury car you'd best take out carpets and do the whole underbody like previously mentioned

edit: ok just saw the whole system thing.
that's a bit harder than just putting in mats.. you'd have to secure wires, lose mounts etc. you'd have to find everything causing the rattle and stop it somehow.
for starters with wires in tight space you would use hardening foam
consult local low rider shops for more info ? heh

 

anyone know of a website that sells this stuff, i just wanna get rid of the rattle in my trunk