To fully enjoy Dinan performance spring sets we highly recommend pairing them up with our supplemental ride quality and handling kits. This additional kit includes tuned, progressive rate bump stops that maximize suspension travel on the lowered car for improved handling capabilities and ride quality when compared to just a spring set. By allowing for full compression travel within the spring the possibility of a sudden "bottoming out" is negated a common unwanted side effect when lowering a vehicle. Bump stops also have the added benefit of optimizing the spring rate rewarding those that use them with added mechanical grip and cornering power. Simply put, the Dinan supplemental ride quality and handling kits amplify performance and comfort when paired with performance spring sets.. Only compatible with xDrive vehicles. Installation labor time is 5.4 hrs if supplemental ride quality & handling kit is installed by itself. Installation labor time will be negligible if installed at the same time as the corresponding Dinan Spring Set. Compatible with stock or other rear shocks with 10mm threads (such as Dinan D140-0945).Not compatible with Dinan D140-0946 rear shocks with 12mm threads and external adjustment.. Bumpstops are made from OE quality material for progressive characteristics.. Dinan Supplemental Ride Quality & Handling Kit - 2007-2013 BMW 335i/335xi. Dinan 07-13 BMW 335i/335xi (E90/E92) Ride Quality & Handling Kit. Bumpstops are carefully tuned for use with Dinan springs.. Includes 4 bumpstops and other supporting hardware.. HANDLING KIT E9X 335XI. Handling Kit. DIN SBSK. E90/E92

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