When I changed swapped my stock PHB for an UMI adj. Rod- / Poly-End-Style PHB I realized that:
Generally: The rear end felt more solid.
- When driving fast through S-Curves (left-right-left) and
- When changing from accelerating to braking (or vice versa) in a curve...
... the car felt really better. The side to side swinging was reduced.
This was even better, when I changed from the 16" stock wheels to 17".
Just my personal experience... Holger