Does a strut brace by itself add to ride harshness?
 

Don't see why it would, if you aren't adding racing monoball hardware. But I'm tired of adding hardware and finding that there is a downside. Thanks.

I put strut braces on several of my cars in the past and didn't percieve any difference in ride harshness. Just improved turn-in and generally made the car feel better planted and precise (in my mind, anyway).

I suppose one might feel a difference in ride harshness if the shock towers were flexing so much that that contributed to a real smooth ride :).

+1

I just installed a strut brace (Weltmeister with modified mounts) and on the street I cannot tell much (if any) difference. At AX, a different story; my turn in was more precise and I was able to rotate the car (trailing throttle oversteer) much more easily.

AFAIK, no down side except for a bit of lost space in the trunk.