What you wanted to do is almost full cabin and fender soundproofing....

1. reduce tyre noise
[KS]Front fender soundproofing (Noise Plug, suppression pad and Insulflex). Back fender = Flex Mat

2. reduce engine noise
[KS]Firewall soundproofing using Flex Mat

3. soundproof 4 doors
[KS]As a starter, you can decide 1 layer or 2 layers. 1st Layer using Propad and Suppression Pad. 2nd Layer using Flex Mat and Insulflex.

4. reduce road noise
[KS]Cabin floor soundproofing. (Flex Mat, Dampening Mat and Noise Absorption Mat)

There you go... Doors are always a good start.

Ok. Not an issue, you can work out the budget. My material and method is flexible enough.

Yes, 4 doors you may use the combination of Propad and Suppression Pad. This is 1 layer.

2nd layer where you want to stick? Door trim? Or the layer with holes for the doors?

Yes, Insulflex and Insulation Foam is the same.

For door trim, you may apply 1 layer of Flex Mat first. Then only overlap with Insulflex Foam. Guarantee nice effect~ !