Aaron's Take
Back in the days when carburetors and direct fuel injection technology was still a norm, the Civic SIR EF9 represented the top of Honda's Civic lineup.
While the lower tier models of the 4th generation Civic were either equipped with only the D-series motors and were SOHC (Single Over Head Cam), the EF9 received at that time, the DOHC (Dual Over Head Cam) B-series motor, along with state-of-the-art fuel injection and what became Honda's ever-popular proprietor technology; VTEC.