Dirt Logic 2.5 Resi Coilovers. From our desert racing experience the Dirt Logic 2.5 has been developed for exceptional performance in a variety of Coilover applications. The Dirt Logic 2.5 will provide incredible dampening capacity for aggressive offroad driving. Features: 2.5" OD Stainless Steel Body. 2.25" OD Billet Aluminum Piston. 7/8" NitroSteel Black Piston Rod. Cold Wound Coil Springs. Adjustable Coilover Construction. 5/8" Spherical Ball Mounting Ends. 2.50" OD Aluminum Reservoir w/-8 Stainless Steel O-ring Hose. Extended Length - E23.13. Collasped Length - C18.64. Stroke Length - S4.49 . Top Mount - TP. Bottom Mount - BPF1.