The manufacturer's ANTI-ROLL-KIT for the 2001-2005 Lexus IS300 is a matched front and rear sway bar set, sized at 28mm front and 17mm rear. Front Sway Bar is Solid and Non-Adjustable/ Rear Sway Bar is Solid and 3 Way-Adjustable. That rear adjustability is the main tuning lever. Compared with stock bars, the manufacturer says the kit reduces body roll and increases grip. It is precision engineered for PRO-KIT and SPORTLINE performance lowering springs. Warranty terms differ between the manufacturer's own pages, so confirm coverage before buying.
Owners on user forums say the rear bar's setting changes the car's balance: setting it to the inner holes shifts the balance toward oversteer. One owner noted that the outermost hole is the closest to stock, and that stiffer settings reduced understeer in low-speed turns but made the tail twitchy at higher speeds. Owners also report that stock stabilizer links can fail under the added rigidity, so fresh end links are a sensible add-on.
Installation is a lift-or-stands job. The manufacturer's instructions say to raise the vehicle securely off the ground using a commercial car lift or jack stands. Owners on user forums report that the rear bar takes roughly 15 minutes, while the front takes some time because you have to remove some protective covers. Long-tail searches for "1st gen IS300 28mm front 17mm rear sway bar" and "IS300 adjustable rear sway bar understeer" match this kit's exact use case.
Owners on user forums suggest the outermost hole is closest to stock feel, with the middle setting a common compromise. Inner holes add rear stiffness and push the balance toward oversteer.
Owners on user forums report that stock end links are a common failure point, and several recommend keeping a spare set on hand. Check the old links for torn boots or play before reinstalling them.
Per the manufacturer's rear-bar instructions, support the bar before disconnecting the second side, because it drops freely once released, and tighten all hardware to factory torque. The manufacturer also recommends a shop manual and a suspension-experienced technician. Owners on user forums suggest loosely bolting one bracket first so the other side has room to align, and they note the front brackets can be stubborn over the bushings. A jack under the bar helps while you work solo.
