Depends on your suspension setup and quality of maintenance. It will definitely exacerbate any issues you didn’t know you had.
I grease all joints liberally on a routine basis, and also use the RS5000X shocks, which are very soft. So the suspension generally does most of the work of absorbing bumps.
At very high pressures, especially over 50 PSI, you’ll start to notice issues with wheel hop going over bumps and potholes that can make hard acceleration or braking a bit more squirrelly. So above 50 does not seem to have much of an advantage. (I have tested from 24 PSI all the way up to 80 PSI.)
Higher pressures absolutely do make the steering feel more precise, which is one of the reasons I run higher than most. Simply put, the less sidewall deflection in a tire, the less “slop” that has to be taken out in order for the tire to begin to resist a lateral load. Up to a point, it also means less static sideslip. (Past a certain point, increasing pressure will actually increase sideslip.)
The other reason I run higher pressure is for the lower rolling resistance. Among a few mods and other things, I get ~18 MPG on 35x12.5 tires now, whereas I got ~12 MPG when I started on 35x12.5, and even only about 14-15 with the bone stock car. That also translates to more available power for acceleration and hill climbing.
Also vastly cuts down on tire wear since the tire has to deform less under load, meaning it stays cooler. Although very high pressures (in excess of 50 PSI) may begin to increase wear due to the effects of wheel hop.
