[RedDevil]

By extending the "wheel air dams" I mean extending them down.
It probably is better aerodynamically to shape a cowl to gradually lead the air away instead of just a vertical slab, but much harder to fabricate - and you don't want to damage other cars should it come loose on the highway.
I once lost a tiny piece of bagel box plastic (a 5" wing shaped sleeve around my antenna stalk) translucent and all, and the semi behind me went full on the brakes... An enormous overreaction, but I felt bad about it anyway.

The thing with tire pressure is that each car is different and you need to find out for yourself what works best. Find a place to test cornering and braking, bring a pump.

FWIW, my observations:
I run about 42 PSI in mine (OEM is about 34) and economy went up about 5-8%.
There's much better cornering with less tire squeal. It was rubbing the sidewalls in hard corners at OEM pressure, which I definitely do not want to happen. Higher pressure means less sidewall deformation and less thread warping in corners.

I have one corner with a wide runoff that I use to test cornering speed. That's 52 km/h max at 34 PSI for my OEM Bridgestone summer tires when new, and 57 km under similar conditions at 42 PSI. That's about 9% more lateral force that the tires can handle!

My car's straight line stability is easily affected by side wind, and higher tire pressure all but eliminates that - to the point that I know I need to check the pressure if I notice the effect; especially on the rears.

Braking in a straight line seems unaffected.
Road noise went up, sadly, and going over 42 psi makes the ride less comfortable. That's the same for all 3 sets of tires I have used on my car so far.