When applying some sound deadening solution such as Dynamat or B-Quiet for the doors, does it make a difference if one removes that plastic film that covers the hole and applies the product around it such as:



Or should one just simply leave that film in place and dynamt over it? It appears that most do the latter, but is there a difference in terms of SQ?




Finally, I assume one should also apply some to the back side of the door panel as well, or is that too excessive and not needed?


Thanks!

 

If you do a search in these forums on Dynamat, you will come up with lots of pertinent threads (and a few alternative approaches). In general, the more treatment you apply, the better your electronics will sound...but then, the heavier your car will be, with reductions in acceleration and handling. That's the tradeoff.

For myself, I consider about 50lbs the maximum I'd add to the car, which should yield decent improvement. Doing the doors will make the most difference, followed by the trunk lid (if you put in a subwoofer), and then the cabin floor and wells.

 

I just did my doors this week, and removed all the plastic, covering the big hole like in your second pic above. You can never hurt anything by adding more matting, unless you are concerned about weight as stated above as well. I considered adding some mat to the outer door skin through the big hole, but decided not to.

I have enough mat left over that I am going to do the areas behind the seats (wheel well area) and the tunnel. I may even go balls to the wall and do the entire floor too. At some point I have to decide if the weight is too much for what I am trying to do. I don;t want' the interior sound level of a lexus, but a slight decrease will be good. At the end of the day, I got this car because of it's performance and fun to drive. Not to make it into a quiet luxury liner.

 

Don't worry, your S2K will never be as quiet as a Lexus, unless you're in a soundproof garage with the engine off, with not a creature stirring, not even a mouse.

I don't think you need to add tons of deadening material to get most of the gains you want. Frankly, I'd be a little cautious about this, because adding weight here and there will change the balance and handling characteristics of the car (in unpredictable ways, which may only show up when you're in the middle of an extreme situation -- remember, no two jobs are exactly alike, and there's not a lot of documented best/worst practices out there yet). The other problem is that if you decide you don't like the tradeoffs in weight/handling you made, undoing it is a big job.

But I agree that you can improve SQ quite a bit with the right components and some reduction in resonance from adding damping in the right places.