Thread: Sound proofing TD5

Apologies if this is an old topic but I cannot find anything specific on the forum. I would like to soundproof my 2002 Disco TD5 so that it is as quiet as the 3000TD Prado around town. I am prepared to spend as much time and mess as it takes but I don't want to spend over $1,000. My initial thoughts/questions are:
1. Is there a low cost meter I can buy to accurately identify and measure the source of noise? My ears tell me the noise is coming through the bonnet and windscreen and the acoustic cover doesn't do much but maybe I am deceived.
2. Surely it must help if I extend the engine bay sound proofing to the sides and further down the trans tunnel?
3. What sort of material is light, effective, durable, tidy, cleanable and does not trap water? I wonder if closed cell sleeping mat is any good? A 1980 Rolls that I inspected had what looked like a quality quilted sleeping bag attached to the inside of the bonnet.
4. The existing sound proofing looks pretty effective on the engine side of the firewall but there are wee gaps in the material for attachements and pipes - should I fill them up with expandit foam or silicon or something else?
TIA

If you drive a soft top 110 with a 3.9 Isuzu then get back in your Disco the Disco will seem very quiet.

Jeff