saab's emphasis was on torque, rather than maximum power. the turbocharged b engine was distinguished from earlier turbo engines by its use of a small, low-mass impeller able to spin up quickly, and the pioneering use of a wastegate to control boost pressure. a feature unique to the early turbo engine was saab's use of the exhaust manifold pressure to modulate the wastegate, allowing boost to decrease slowly at high engine speeds. this resulted in a broad, usable torque curve. power was up 23% over the naturally aspirated version, while torque rose 45%.