Not just make them quicker, but the goal was to still look ‘stock’. I have seen an interesting documentary on it, really interesting. I wondered why it was called ‘stock car races’, when they are anything but ‘stock’. Just supposed to look that way, but the engines and shocks were 2 of the main upgrades. Engine to outrun and shocks to not give the appearance of a very heavy load of illegal goods...
I cannot squeeze all this down to just a few words, but I will offer this:
The difference between ‘stock” cars & MODIFIED cars is quite a bit.
Hard to use just a few words here.
Try to find where the nearest “MODIFIED” cars are running near where you live & avail yourself of such an evening’s entertainment.
Just for starters—the exterior sheet metal is quite different. Tire stagger—lots of things.
That would require a change of springs, not shocks.