THE mighty Scooby is back in business with two big boost turbos returning to the Subaru stable.

One is a venomous Cosworth special pumping out a monstrous 400 horsepower and with an equally monstrous £50,000 price tag.

The other is a little more sanitised at 320ps and priced from £32,995.

Such firepower is enough to grab the attention of the army of fans who have been enthralled since the moment the first Impreza Turbo hit the road almost 20 years ago.

Its success on the world rally stage gave it a heady status enjoyed almost exclusively by Subaru and its great rival, the Mitsubishi Evo.

The latest Subarus are in the true spirit of the original yet brought bang up to date with plenty of technology.

The Cosworth is an inspiring flagship for the current Impreza hatch range and uses a high boost turbocharger to take the power from the 2.5-litre flat four boxer engine to almost unimaginable levels.

Acceleration is in the supercar league at 3.7 seconds 0 to 60 and its topped speed is capped at 155mph.

It is testimony to the Subaru chassis that it can take such power and to cope with the demands the suspension and damping have both been uprated.

Yet despite all-wheel-drive and sophisticated traction control systems the Cosworth is almost too much for the road.

Cranked up to its extreme in Sport Sharp setting it can get twitchy and the multi-mode drive control is best left either in its Sport or the so-called Intelligent position where the car is supposed to work things out for itself.

The same goes for the variable differential control which can shift power from front to rear bias - don't dabble unless you are an expert.

Nevertheless the noise from the turbo and the gush from the waste gate should be sufficient to hammer home that this is not a car for the faint hearted.

As great Imprezas go the Cosworth STI is definitely at the extreme. Perhaps its running mate is a little more in keeping with the feel of the original - and this version also comes as a saloon which will help satisfy the purists.

Although the Impreza name has been dropped - the car is now known just at the WRX STI - it certainly looks the part with a hefty air scoop on the bonnet, skirts and spoilers.

The car features a power upgrade from the standard 300ps - the modification is carried out by Subaru in the UK - and it shaves 0.3 of a second from the 0 to 60 time taking it down to 4.9 seconds.

It is fun and demanding to drive - just as the original - and the cockpit is delightfully straightforward.

The seats are firm, the ride is harsh but the car is very responsive and kicks like a mule.

Compared to the turbo of the 1990s which had only 284ps on tap it is not quite as engaging but that's down to the modern day electronics which reduce some of the feel.

That said, the WRX STI delivers sure footed and raucous fun which puts it in a class of its own for the money - and surprisingly it's not that thirsty.

After an enthusiastic drive through the Cotswolds we saw an average 29mpg on the trip computer - and that exceeded the 27 to the gallon officially claimed by Subaru for the lesser powered WRX STI.

The Cosworth production run is confined just to 75 models - making it very collectible and there's still a few to be snapped up - while the 320ps power upgrade on the WRX can be had to order. At the moment Subaru is offering it for free but come the New Year it will cost an extra £799 and if you want sat nav that will stick a further £750 on the price.

In these days of eco machines and near paranoia over exhaust emissions this pair may be regarded as black sheep but for those who crave really hot motoring it doesn't get much better.