Subaru Legacy B4 RSK Twin Turbo
The Subaru Legacy B4 RSK was the ultimate Q-car — a car that looked like a modest Japanese sedan but packed genuine sports car performance. The 2.0-liter flat-four engine featured Subaru's sequential twin-turbo system, where a small primary turbo spooled quickly for low-end response, then a larger secondary turbo took over at higher RPM for maximum power. The result was 280 hp (Japan's gentleman's agreement limit) delivered through Subaru's renowned symmetrical all-wheel drive. The Legacy B4 RSK could demolish most sports cars from traffic light to traffic light while looking entirely inconspicuous. The flat-four engine's low center of gravity and Subaru's well-sorted chassis provided handling that belied the sedan body, while the all-wheel drive gave all-weather capability. In Japan, the Legacy B4 RSK was a favorite of businessmen who wanted serious performance without the boy-racer image of the Impreza WRX STI. Today, the B4 RSK is appreciated by enthusiasts who understand that sometimes the best performance car is the one nobody suspects.
Check for head gasket issues — common on EJ20 engines. The sequential twin-turbo system is complex — verify both turbos spool correctly. AWD system needs regular fluid changes. Rust in wheel arches and sills on older cars. Many JDM imports available but verify specifications and mileage.
The EJ20 flat-four with sequential twin turbos was one of Subaru's most sophisticated engines. The '280 hp' was Japan's voluntary power ceiling — actual output may have been higher. JDM-only specification with many features not available on export Legacys. The B4 designation indicated the sedan body.