This new turbocharger plays a large part in the improved performance from the two-litre engine and is positive proof that less is more. Gone are the twin turbochargers of the previous model Legacy RSK B4. The new motor has stronger mid-range torque and improved throttle response thanks to the titanium turbocharger; the improved engine management system and the 'drive by wire' throttle system.

Titanium is a strong yet light material that was developed for military hardware and the space exploration programme. But its increasing number of widespread uses demonstrates its more practical side. Titanium is now used widely in motorsport, yacht racing and even competition bicycles.

In the Legacy GT's turbocharger, the titanium is used in the turbocharger turbine, which is 30 per cent lighter than the turbines used in the previous twin turbo model. Thanks to its light weight, the turbocharger will spin up to its best operating speed much quicker than the turbines used in the older Legacy RSK B4.

While the peak power of the new car remains the same at 206 kW, the all important peak torque, or pulling power, is produced much lower down the engine revs range. On the previous Legacy twin turbo model the 343 Nm was delivered at 5000 rpm as the twin turbos took longer to rotate up to their best operating speed.

Now the same 343 Nm is available from 2400 rpm, giving the Legacy GT that V8-like engine acceleration that so many Kiwi drivers like. Now the maximum torque is produced within the power band that the majority of drivers use most of the time.

It provides up to 40 per cent quicker throttle response for faster and safer overtaking manoeuvres on the open road without the need to change down a couple of gears. 'Turbo lag' which characterises so many earlier model turbocharged cars is a thing of the past. There is now a seamless surge of more accessible and instantaneously available power with the twin scroll titanium turbocharger.

The titanium turbine has a larger diameter to provide the greater driveability from the engine. In the past larger diameter turbines produced high power outputs but suffered from 'turbo lag' because they took longer to spin up to their best operating speed. The lightweight titanium turbine negates that potential problem.

The turbocharger's performance is also aided by the twin scroll system of feeding the exhaust gas into the turbocharger. In the past, a single pipe has fed the exhaust gas into the turbocharger.

Now there are two pipes, one from each bank of the 'boxer' engine. The exhaust gases, which propel the turbocharger turbine, are fed faster and more directly to the turbocharger, resulting in the better throttle response, minimised turbo lag and the wider effective operating range of the turbocharger.

Getting the exhaust gases to the turbo more quickly provides more gas to accelerate the titanium turbine, which spins up to operating speed faster.

Complementing the titanium turbocharger is the twin exhaust system, with twin rear mufflers and tail pipes. This helps 'drag' the exhaust gases out of the motor faster, promoting better low and mid range torque for that V8-like performance.

The final component in the titanium turbocharger's operation is the 'drive by wire' electronic throttle control system. A broken throttle cable is a thing of the past, as there isn't one to break! Instead the driver's intentions are conveyed from the accelerator pedal to the engine electronically rather than by a cable. This cuts out any jerky throttle operation by the driver, smoothing out acceleration and deceleration. With the throttle's electronics integrated into the engine management system, fuel is delivered more smoothly, providing better throttle response and better fuel economy.

The twin scroll titanium turbocharger is a positive demonstration of the constantly evolving technology in the latest Subaru, making the Legacy GT an exciting yet at the same time relaxing car to drive.