With a carefully selected outer diameter of 25mm, the iE rear sway bar upgrade achieves the ideal balance between optimum performance in the twisties and maintaining a comfortable ride in your daily journeys. Combined with our one-piece spring steel design, this diameter increases stiffness upt to 104% over stock, enhancing control in the turns. Our thoughtful sizing maintains a smooth and comfortable ride without excessive vibrations or harshness with all the exhilaration of spirited driving when you want -truly the best of both worlds.