Sound Deadening Underlay for Trunk Area

Reading this Forum not so long ago, I came across a recommendation from somebody for an inexpensive but effective sound-deadening underlay for the trunk area of a 928; I seem to recall that it was was some sort of ground-sheet material that would be used for camping. For the life of me I can't seem to find the reference. Can anyone help?
Dave

Dave - I do not remember that specific post, but I do have a couple of ideas. Right now I am using a piece from Robert Budd, specific to our trunk layout
www.classic9leathershop.com/
and it works very well,,, if you want to go even cheaper or do it yourself, just search online for sound deadening material (fiber or foam) and cut it out yourself. I had done that until I got Robert's product, which was superior in deadening and also helped keep the heat below. I also recommend, before you do either to also buy the cheaper version of the stereo sound deadening material (not Dynamat) that is sticky on one side and reflective on the other, comes in a roll, you can cut it with industrial scissors, that also works pretty well, I think Noico has that style. I do not see what I bought a few years ago.. but it is still working for me, and if you use a combination,,,, I think you will be pleased with the deadening properties.

Thank you, mm28. I have not had time to look up the references you suggested, but will let you know how I get on. Incidentally, I note that with the same (factory) sound deadening underlay as in my 1985 928S, the sound level in my 1989 GT is significantly higher : I guess this could be due to noisier tires, or stiffer springing?
Dave

I have used the underlayment foam from Robert Budd - it is the same as from Jager I believe: www.jageng.com/garage9/product_info.php?..._100&products_id=568

This set includes the front footwell and trunk/hatch area, but not the rear footwell. I made some for the rear footwell in both my cars, and for the front footwell in my '88, using a closed cell camping mat from Canadian Tire (you may have seen that in a previous post of mine). Earlier 928s (including my '88) had floor mats with padding that looks like some kind of plant fibre. Later ones had integrated foam that is shaped to the floor pan profile. I have such in my '90, but not in the rear footwell, but GTSs have it in the rear footwell too, so I deduce Porsche determined it is beneficial.

I agree with mm928, acoustic deadener (I used B-Quiet: b-quiet.com/ ) also works very well in conjunction with closed cell foam - they serve a different function - one to isolate/absorb (the foam) and one to dampen. I used B-Quiet under the mats in the footwells and hatch in both my 928s. B-Quiet also sell a composite that does both - I haven't used it yet.

Some people also tackle the rear wheel well/B-pillar area. I addressed this with both B-Quiet (on the actual metal wheel well surface inside) and absorptive padding in the space below the speaker (I use a recycled denim material that I find works well) by accessing it through the speaker hole. Porsche added foam to the backside of the rear wheel well liners of 928s, in addition to the rear footwell foam I mentioned. I have considered this, but frankly now my '90 is very quiet with what I have done so I haven't bothered trying it.

Tires can make a huge difference. My '90 had aged tires when I got it and it really roared. With new tires it is significantly quieter, even tho the type I got Adam found to be louder than others .