Powerflex USA - BMW E36 / E30 / Z3 / Z1 Front Lower Control Arm Rear Bushing - Aluminum Shell (Centered)PFF5 5301 includes a CNC machined aluminum outer shell with a concentric bore for standard geometry alignment. With the machined shell, and reducing the amount of polyurethane material used, we have increased stiffness by a further 50% over PFF5 301 and PFF5 303, and a massive 250% over the standard OE rubber bushing. The results are incredible, with minimal deflection under steering load and braking, while maintaining a balance of compliance and