Throughout the 9th-generation Civic Si's life, Honda continually made revisions to the front and rear stabilizer bars and steering ratio. The launch model was the softest of the batch as it featured a 0.71-inch front and 0.6-inch rear bar with a steering ratio of 16.08:1, giving the wheel a lock-to-lock rotation of 3.11 turns. One year after this, the engineers tightened things up by increasing the bar thickness to 0.83 inches on the front and 0.71 inches on the rear. The steering ratio was shortened to 14.94:1, providing the wheel rotation with a shorter 2.87 lock-to-lock turns. Honda continued pushing the limits of stiffness with the arrival of the facelift as the rear stabilizer bar was increased to 0.79 inches. The steering wheel's lock-to-lock was shortened even further down to 2.78 rotations.
As the Civic Si is a halo model, it comes fitted with a power sunroof as standard together with air-conditioning with an air-filtration system, central locking with an auto-lock system, cruise control, a leather-wrapped multifunction steering wheel, and aluminum pedals with a complementary shift knob. Both the coupe and sedan are treated to an armrest and air vents for the 60:40 split rear bench.
Pre-facelifted Si models employ a traditional audio unit connected to a premium seven-speaker system including a 360-Watt amplifier and subwoofer. This features an auxiliary, Bluetooth, and USB input together with the usual MP3, CD, and radio compatibility. Selecting the optional navigation package will add a 7.0-inch infotainment screen with Sirius XM, FM traffic updates, and voice recognition. Without this, the display configuration is still comprehensive thanks to the intelligent multi-information display (i-MID) which showcases information such as average fuel economy and speed, the odometer with two trip meters, elapsed driving time, exterior temperature, and fuel range. It also lets you customize the door locks, interior lighting, screen colors, and wallpaper.
The facelifted Honda Civic Si is a slightly more comprehensive offering as it adds keyless entry with a push-button start, a sliding armrest for the center console, and a 7.0-inch infotainment screen acting as a display for the backup camera. The navigation package adds HD and XM radio, voice recognition, and FM traffic updates. Dynamic guidelines are also included for the multi-view backup camera.