Progress Sport Spring Kit Scion xB/xA 04-07 Model: Progress specifies only certified high-tensile SAE Spring wire materials. The Springs are cold-wound on modern CNC coiling machines, then stress-relieved, pre-set and shot-peened for maximum durability. Springs feature aggressive lowering for significantly improved appearance, increased rates for upgraded handling capability, and progressive spring designs for superior ride quality. Part Number 40.2170 Approximate Lowering Amount & Spring Rates Front Rear 1.3” 1.2” xA 1.8” 1.5” xB 165 lbs. 175 lbs. These are now available in our “New” charcoal gray powder coating and always offered with our Limited Lifetime Warranty.