9 October 2002: Subaru’s Impreza WRX STi can now be fitted with a 305 PS performance pack giving a 155mph top speed and 0-60 mph time of only 4.6 seconds.

Developed by British company Prodrive, the power boost involves 2.5 hours for dealer fitmentand increases the power from from 261bhp.

The result is not only startling high-rev performance but also more low and mid-speed flexibility.

Side-by-side tests revealed a 0-60mph time down from 5.2 seconds to 4.6 seconds and a 0-100 mph figure of 12.2 seconds instead of 13.7 seconds. Quarter mile figures are now 104.7 mph/13.4 seconds instead of 101.4 mph/14 seconds.

The performance pack produces more pulling power between 3,000 rpm and
5,800 rpm than the standard STi has at its peak, while at 2,500 rpm, the car has almost 30 per cent more torque.

The pack – which carries Subaru’s full three year/60,000 mile warranty – comprises a revised engine control unit (ECU), high-flow catalyst and sports silencer. It costs £1,995 fitted in Britan.