With any GranTurismo/QP you need to get them up on a ramp and inspected. They really are not doing well in that department.
Chassis plates, well we all know they disintegrate but are simply a bolt on part so easy. The main are of concern is the triangular box section of the front subframe that runs between the upper inbound wishbone mounting points. Water sits inside it and they rust from the inside out.
Poke it with a screwdriver, chances are you will go through it on most 8-10 year old cars and older.
If there is one thing you spend money on it should be an underbody corrosion treatment and seal.
All the pipes/unions are tarnishing badly too.
The other common are we are seeing is front upper wishbone bushes. They last 25-30k and no more.