NorCal Nick installed the Sulastics for me last week. They eliminate that immediate spring-to-frame harshness induced at every bump. They also eliminate the annoying vibration in the leaf ... the feedback-whip vibration (spring-stutter?) immediately after a bump. The Bilsteins had already tamed it quite a bit, but the Sulastic shackles totally damp it out.
Just back from 300+ miles on NorCal freeways, and I'm totally satisfied with the Sulastics, drop-version. I don't have airbags, but Nick's white dually has them plus the Sulastics for everyday comfort. His CC dually rides exactly like my XCab.
2007+ LMM SilverBirch Sierra 2500HD 4x4 ExtCab SLT;
RacingEdge Evolution (+105) & MBRP (Quadzilla Stealth & standard Evolution & DPFkup, all retired);
Pirelli 305/55x20E (33 x 12s) on Incubus 505s (20x9 +25 offset) on Bilstein 5100s, Cognito braces & dropped Sulastic Shackles (by NCT-Nick);
Full swap to Amsoil Syn fluids, EaO filtration, Allison deep pan plus TransGo Jr. shiftkit.
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NBS Tire Garage / Installing Wheelhouse Liners / My Garage