My car is heavily soundproof, yet it can't eliminate all the noise, especially tyre noise. The final solution for me is to change tyre 7k km more later.
Ok, basically BLM noise can be divided in 3 categories.
1. Tyre and road noise. (most severe)
2. Engine noise.
3. Part vibration noise such as dashboard, power windows bracket, door lock mechanism and all the plastic things inside your cabin.
So far my countermeasure for that:
1. Soundproof fender and plastic wheel arc. Done at acc shop - reduce front tyre noise effectively, and reduce engine noise and wind noise coming through the fender as well.
2. Whole floor and boot soundproof and deadening. This can reduce tyre noise effectively, and road noise echo is eliminated. Front floor soundproof depends how deep they extend into firewall, for my case, after soundproof the engine noise is reduce gain. Whole floor done outside, while boot area DIY.
3. All doors 3 layer deadening and 1 layer soundproof. Front door soundproof can reduce engine noise, front tyre noise and wind noise effectively, and this kind of heavily deadening totally eliminate the rattling sound of the door and power windows, this can't be done by just apply insufflex. Door soundproof is DIY, i will say, damn tiring.
4. Cheapest way to reduce engine, tyre and wind noise, change your door soundproof rubber, you can search at Chinese Cari forum, that one is OEM rubber, fit perfectly and not like the sticker type that sold at automotive garage here. I would say the C/P ratio for this one is the most highest one.
Now only left firewall, will left it 1st, because now my car engine noise is reduced almost 50% after i done all the soundproof and deadening above. The remaining one is tyre low frequency noise.
All the work above is done gradually over 4 months.
thanks for all the ideas and exp, i'll take it to heart, really appreciate all exp from you all... hm....