The H&R 29122-3 is a progressive-rate sport spring kit for the all-wheel-drive 2006–2013 Lexus IS250, sold as a direct replacement for the factory coils. The manufacturer lists the AWD kit at 1.4 inches front and 1.3 inches rear (approximate). The springs are made from 54SiCr6 spring steel and shot-peened by the manufacturer, which is the material used for the brand's performance coils. Compared with a generic lowering spring, the reason to pay for this kit is the documented drop, the tested steel, and a progressive rate that aims to reduce body roll in corners while keeping the ride tolerable on daily commutes. Searching for "IS250 AWD sport springs 1.4 front 1.3 rear," "H&R 29122-3 install," or "progressive rate lowering springs IS250" should bring up the right kit.
Make sure you order the AWD version. The manufacturer's application table lists 29122-1 for 2WD and 29122-3 for AWD, so the drivetrain is what separates these two kits. Because the springs are a direct swap, they work with the factory dampers, and the install is a manageable driveway job for a home mechanic who is comfortable with strut and control-arm work. Owners on user forums who have done AWD IS-series spring swaps report that the front can often be done without disturbing the sway bar link or ball joint, though the AWD front shock uses a different lower bracket that you will need to account for. Confirm torque values against a service manual before you finish.
The manufacturer's application table pairs 29122-1 with the 2WD IS250 and 29122-3 with the AWD IS250, and both list the same approximate drop of 1.4 inches front and 1.3 inches rear. Check your drivetrain before ordering.
Owners on user forums who have done AWD IS-series spring swaps report that the front can usually be done without disconnecting the sway bar link or ball joint. Forum experience varies, so verify the procedure against a service manual.
This is a moderate-difficulty job that suits a home mechanic with a floor jack, jackstands, a torque wrench, and a breaker bar. Use a proper spring compressor when working on the front struts, because the springs store a lot of energy. Owners on user forums who have performed similar IS-series swaps note that the AWD front shock has a C-shaped lower bracket that changes how the strut comes out, so look at that before you start. Forum posts for closely related IS platforms cite 76 ft-lbs for lug nuts and 87 ft-lbs for a ball joint nut when that joint is separated, but these figures come from a different model year and drivetrain, so confirm them for your car.
