I previously had a 2010 III with 15" Yokohamas and the handling always felt loosey goosey on the freeway. The Toyo Proxes handle much better... more stable, solid feeling on highway and on curves, turns. I know some say they are supposed to have sidewall weakness and prone to blowouts. I wonder if that's true.
I got about 3 years & 60000 miles out of my OEM set. tp was max sidewall pressure from Day 1. No handling problems even during rally and autocross. I suspect you are more likely going to have an adventure with 34psi in them.
I notice that once you go up in PSI(40), road noise increases substantially. I had them at 35 and they seemed a lot quieter on the freeway. In regards to handling and road feel, I give them a 8 out of 10. I think the limited factor has not been the tires but suspension.