Thank to the feedback guys, I really appreciated it!
IMO you should have kept the bound as low as the body is, but then it would be even lower than the default GTR-1 and the car won't get on sidewalks.
The bound is not really realistic but that's to make the car more playable. If I made the bound covering the entire car, it would be hitting the floor all the time, only in really plain road it would not happen because it's really low. Playing in San Francisco with it would be totally impossible because it could not drive in that inclined roads, and even in London would be really hard.
Okay, it's a racing prototype so the biggest fun you can have with it is in addon racing tracks like Brands Hatch (my favourite racing track), but even in them the bound would cause some bugs.
I was already expecting somebody talk about the bound because I also don't like when I see the bumpers passing through the floor, but in those situations is good to remember if the bound was realistic you could not drive in that place.