It's something I kinda learned, I didnt think the percentage was that low...but it probably is.
since grip is a function of friction, the only thing touching the groud are your tires..thusly grip is a function of tire type, compound, and design more than spring settings, so much as the suspension can keep the tire in contact with the ground(with respect to the tires grip)
this is why all-out race suspensions suck with street tires

and street suspensions dont do well with race tires....
but, you would get better cornering and handling by just chaing tires than springs/shocks/swaybars...
dennis actually has some kind of math to prove it, but its something "I've seen in test after test....
the funny thing, I've seen "celica stock .83G, hotchkiss celica .96g" and people go "see! look! 10%+ increase!"
...from stock 16" H rated tires to s-03 in a sticky 17"....what did you think would happen? hehehe..make sense?-chet