Quick, high angle steering. Snappy, high impact transitions. Dramatically improved handling on lowered cars. This is our famous Forged Super Angle Knuckle with roll center correction. ~ Forged steel with CNC finished mounting surfaces for strength and symmetry. ~ Gold Zinc Plated ~ 45mm roll center and bump steer correction ~ quick steering ratio ~ up to 70 degrees of angle when equipped with our full front end set of supporting parts ~ Approx 4 to 8.5 degrees ackerman at high angle depending on rack location or use of offset rack spacers. Offers a natural driving feel ~ This is a brand new part ready to bolt on with no core charge, no modification to your OEM knuckle, no two way shipping fees, no down time ~ S13 has a 30mm spindle and S14 is a 34mm spindle, They also differ in the FLCA taper, hub compatibility, and coilover hardware is M12 on S13, M14 on S14. If you put an S14 knuckle on S13 you'll drill your coilover lower mount holes bigger & you'll be mising a spindle nut washer we sell separately. ~Compatible with OEM tapered outer tie rods or MAX part # OTRT and OTRLBT.