To install your Outlaw Stiffy springs, simply remove the spring cap at the rear.
If you are installing the Large Stiffy springs, decide whether you want to keep the skinny inner spring or not. If you keep it installed inside the red stiffy springs, you'll increase the stiffness from stock springs by 22%. If you just use the red springs, you'll increase the stiffness by 13%, but you'll have more work to do.
If you just want to use the red springs, you'll need to reverse the centering screws at the front of the slide tubes. First remove the slic pins and flex plates. Press down on the flex plates and rotate the slic pins if they are stuck. Then use a T25 Torx driver to remove the centering screws from the steel plate at the front of the springs and slide tubes. Next reinsert the screw from the back of the plate, then install the red stiffy springs, spring caps, and flex plates.