Thanks for all the additional insight. I do have some db readings that were taken prior to installing the material. ( I took them to gauge the sound quality of my stereo system) I will take additional readings and post them later today. As far as access to tank, sender etc., we laid a small amount of wax paper over important areas so that it would be a little easier to get to those areas is needed.
I had also purchased and installed new splash guards and foam inserts from Roger but plan on doing something about the cavities also.
Thanks again for all the experienced advice.

Lon

 

Try checking the door and hatch seals for leakage - lots of strips of paper (~2" wide, 12" long) - lay a bunch along the sills first, shut the door, see if any of them pull out with no resistance - if they do, the seal has failed there. It will probably take a helper to hold strips in place for the top and sides of the door jamb, and similar for the hatch.
jp 83 Euro S AT 55k

 

Lon,

You can also remove the rear 6" speakers, insert a plastic grocery bag in the cavity below the speakers, then fill the bag with expanding foam.

 

Thanks for the additional advise Don, I plan on using the expanding foam in the cavity areas and using your idea of a "plastic bag" will go a long way in controlling the mess and splattering I had anticipated...Thanks!
Also, jpitman, did the leak test along the sills using strips of butcher paper, also sat inside while my son sprayed high pressure water all along suspect areas. ( Don't drive in the rain as a rule but loose seals would contribute to cabin noise which is what I am trying to reduce) everything seems tight and I will do a 70+ mile road test to confirm it weather permitting.
Thanks again for all the advise.

Lon

 

Just a word of caution filling the B-pillars with foam. That is where the cabin exhaust is expelled and on out through the louvers on the lower A-pillars between fenders and front door edges. If you block off that exit you may get fogging/misting issues in the cabin. A car cabin is designed to expel air in a controlled flow. If you close off the exhaust route for the cabin air, it will find other ways to escape, most likely through the door seals which will cause noise...kind of defeats the purpose of this exercise in the first place. Below is a Porsche diagram of the cabin air route.

Cheers!
Carl

 

Thanks Flymo I recall reading another post on that and your diagram really helps explain in pictures which I usually need....