$385 here for SuperSprings (SSA28) - 3,000lb capacity. Sharing this for the review comment below. I'm interested in what you hear back from the company, but this review says a lot.
SuperSpring Helper Spring Kit, Medium Duty, Suspension Stabilizer, SSA28 - TruckSpring.com
Comments about SuperSprings SuperSpring Helper Spring Kit - Medium Duty:
I put these, SSA28, on my F-150 Raptor/SVT when I need to haul some extra weight. They need to be mounted slighly offset towards the rear to gain sufficient clearance between SuperSpring front shackle and truck frame when and only under xtreme heavy load. Front shackle of SuperSpring should be approx. 2 1/2 inches back from front leaf-spring clampholder. That will bring the rear SuperSpring shackle right up next to the rear leaf-spring clampholder. As the truck leaf spring compresses, it elongates rearward, still allowing for clearance. I know this thru trial/error.
These can be left on if not baja-ing.
They will raise the back of truck 1 inch+.
They give a slightly stiffer ride, but a better launch. It takes longer to jack the truck up, than it does to install or remove the springs.
Simple job. Now, I have a Baja & Payload Raptor.
Service and delivery comments:
I chose these guys (trucksprings.com) because they have been around . . . almost as long as me .. well, since the Twentieth Century.
Clean,Fast,Priced Right, Order = happy camper
BOTTOM LINE Yes, I would recommend this to a friend