update
Had the underlay under the carpet removed and replaced with Silent Coat 2mm and Silent Coat foam and put the original carpet back on. I did clean the back .
the stench is pretty much gone! I will probably have the carpets shampooed as the stench from the underlay really did soak in a little bit into the carpet. But the smell is considerably gone.
There is additional material right inside the dash area. But I am not willing to pay someone for two to three days and in the 4 digit price to get the job done. So far so good though