SPL Parts Swift Assist Springs 65mm Spring Rate 335 lbs/in (SWIFT-A65-060) 3518 and/or 4" round resonator

and/or 4" round resonator

CSF Heavy Duty Intercoolers are the perfect upgrade for your 08-10 Ford Super Duty 6

E Quality Viton Seals:

In addition to the parameters of your choice

BHP: 707 2018 Dodge Challenger Engine: 6

SPL Parts Swift Assist Springs 65mm Spring Rate 335 lbs/in (SWIFT-A65-060) 3518 and/or 4" round resonatorAssist Springs Get the best of both worlds, Swift assist springs provide a dynamic step linear rate. Like our helper springs, the assist springs are designed to be fully compressed at static height. Every one of our assist springs compress to the exact same height. This allows drivers to change assist springs without resetting the perch on the coilovers so the ride height isn't affected. Heavier rates of assist springs over helper springs are used to