This front swaybar (aka anti-roll bar) fits the 2006-11 Civic. It's an upgrade for both the Si and non-Si models. I usually recommend this with a larger rear bar, like the 22mm or 24mm Progress bars... A front and rear bar upgrade really transforms you Civic with slot-car-like handling. You can also just get a larger rear bar for starters. Many people who run stiff coilovers actually rather the stock front bar and a huge rear bar because the stiff coilovers serve to tighten the front up enough that a larger front bar isn't needed. But when running stock or any lowering spring (especially when not running much front camber), a larger front bar can actually improve speed through a turn by keeping the car from rolling and therefore keeping the front tire's contact patch on the ground.