Swapped out those worn-out shackles for something with a bit more oomph, now the rear is tight as a drum and my chassis can really work its magic on the track.
Swapped out the old ones for some stiffer units that should help with cornering and braking on the track, feeling pretty good about it so far.+1 de plus
Ran through the suspension calibration process, made some minor adjustments to get the spring rates just so and now the car feels tight and predictable on the track.+1 de plus