With the WRX STI 340R upgrade, which costs an extra £1599, the all-wheel-drive car boasts 335bhp and 361lb ft, increases of 39bhp and 61 lb ft over the base car.
The 340R power upgrade features different ECU settings to allow the 2.5-litre, four-cylinder boxer engine to produce more power, while airflow improves as a result of a new exhaust system.
The WRX STI 340R accelerates from standstill to 60mph in 4.7 seconds – half a second faster than the standard WRX STI.
It is available alongside the less-extreme WRX STI 320R power boost, which you can read more about here. The 320R kit takes power to 316bhp and peak torque to 332lb ft. Both upgrades can be fitted retrospectively without affecting a car’s warranty.
As with other WRX STI models, the 340R has a Torsen rear diff and fully independent front and rear suspension.