Yo Bro, I am wayne, the white myvi did the chassis foam + A-pillar on 3/10 Sun. Here is my review:
1) Not immediately feel after foamed, but after 2 days, magic happened! The first thing i noticed was my steering became tighter(is it called "better handling" ? i m a noob in car).
2) Solidness of the chassis increased, as I passed through speedbumps or road holes, you can hear a very solid and bassy "thum" sound...And to my surprise, the interior noise reduced alot! Perhaps the reason is chassis has been strengthened?
3) Wind and Road noise dampening can't really feel, it is as loud as usual.
Anyway, if you are looking for chassis strengthening, this product really works! Bro, I saw some foams are still attached under the chassis hole, mind to help me trim it? hehe