Nothing of all that will help you.
softer springs = car bottoms out too much
stiffer springs = less grip, twitchy handling
higher tire pressures = less grip = more sliding = bad tire wear and even higher temps
car weight, umm, it would help if you could get rid of a few hundred pounds, but moving it around won't help

I haven't heard of that update yet, and that line you posted is enough to know that I don't need it. Lowe's isn't actually the most challenging track in the game anyway, so there's really no need to make it even more boring by adding some kick ass grip.