The biggest difference between a consumer car and a luxury "vehicle" is the amount of sound deadening material used. Quiet car = Luxury car. I think your best bet is to try and make friends with local car stereo installation shop. They know what materials work. You're going to want to do under the carpets - floor, doors, and if you're up for it, the headliner.

 

The biggest difference between a consumer car and a luxury "vehicle" is the amount of sound deadening material used. Quiet car = Luxury car. I think your best bet is to try and make friends with local car stereo installation shop. They know what materials work. You're going to want to do under the carpets - floor, doors, and if you're up for it, the headliner.
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Has anyone ever put sound deadening material in their Sienna's? If so, what give you the best results, like doing the floor, or doors or wheel wells?

I don't have a Sienna, but I've done two cars. You will get the greatest benefit by doing your doors first. Then do the larger side panels on your van and then the wheel wells. Floor pan and head liner last (if at all). When I did my car I removed all but the dash (door panels, seats, carpet, all trim and headliner) I also did the trunk, trunk lid and the hood. I did a lot of research prior to selecting the CLD for my current car. I went with Kno Knoise Kolossus for CLD. In independent testing that I found, it was second only to SDS tiles (no longer available due to maker retiring). I also used 6mm CCF, butyl rope and Tesa tape. I've personally had experience with other CLD and vouch for the efficacy of the Kolossus. My experience has been that the higher quality product gives the best results. Time and effort involved will be about the same regardless of the deadener you use. DON'T use asphalt based product.

There is some good reading on the ResoNix site on theory and application. His products look very good and I wouldn't hesitate to use them, but I already had my materials when his product became available. It appears that his tiles are an attempt to fill the niche left when SDS tiles became unavailable.

I'm a stickler for detail, including in the quality of my sound system. I want a very quiet environment and consider my car to be my audio escape pod. I listen primarily to classic rock, blues, jazz and a little classical. You can see a brief synopsis of what I did on my car in my signature. If you have any questions, PM me.

 

Now that is good information, thank you very much!!!

 

If there is a second layer of sheet metal how important is it to cover it?