PFF5-5303 includes a CNC-machined aluminium outer shell with an eccentric offset bore, increasing caster by 6.5mm / 0.5deg, for better turn-in response and in-corner camber gain. By including the 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 bush. The results are incredible, with minimal deflection under steering load and braking, whilst maintaining a balance of compliance and performance.