The 2.0-liter, dual-overhead camshaft K20Z3 engine in the Civic Si produces 197 horsepower at 7800 rpm and 139 lb-ft of torque at 6100 rpm. Thanks to special Honda-developed performance technologies, such as the ultra-precise Drive-by-Wire™ throttle system,™ 3-rocker i-VTEC® variable valve timing, a cold-air intake and equal-length exhaust header, the K20Z3 engine boasts a flat torque curve from idle, all the way to its race car-like 8000-rpm redline. Plus, the K20Z3's intake and exhaust system is quiet and unobtrusive when cruising at highway speed, but produces an aggressive, sporty sound at full throttle.