[axsaxoman]

stiffer the chassis ==the better the suspension works
track car is where you are wanting the best is it not ?
ideally the roll cage should bolt direct to suspension mountings where possible to transfer load to something that will not flex
hence if allowed you have the cage coming down on to strut heads + why you seam weld shells +add bits
std car is meant to fold up when in a bump and crush in a controlled way
race car you want chassis solid --so if you have an excursion to the barriers or a wee roll --its only wings and things you have to replace --and main shell stays straight
same reason F1 cars want wishbones to come off before it damages the main "tub"+ suspension pick up points--just bolt new bits on

not really convinced that this kit will do that much + we are talking about small amounts here --as those mounting points for wishbone are where all the layers of chassis ,4 layers i think come together --but unless you spread the load further than it is as std you are still going to have it flexing in the floor pan .
I drilled through all the layers on my car and mig plugged all layers together+seam welded underneath
tacking these plates on top assumes the spot welds are good below
jack car up at front corner --then open door --bet it won,t shut easily if no cage fitted

this not an critisim of the kit supplied ,.i,m not having a go at them --but if you looking for a measurable increase in chassis stiffness --then that on its own won,t do much