Group Test: The Ultimate Air-Cooled 911

993 multiplied by three equals an awful lot of fun...

There are days in this job when even including Claudia Schiffer and copious amounts of honey could not make it better. This is one of them. Myself and RacingPete have made the pilgrimage to Specialist Cars of Malton - a used Porsche specialist in the small Yorkshire town of the same name.

Why pilgrimage? Because, for the committed Porsche-phile, Specialist Cars is a truly holy place. Behind the utterly unpretentious industrial estate façade lies a jaw-dropping treasure trove of Porsches old and not-so-old.

But it's not the green 1974 Iroc 911 RSR that we're here for (dribble), nor the immaculate but intimidating Carrera GT (drool). Instead, there are three very special 993-era 911s sitting on the forecourt, waiting for us.

Brightest in colour but most modest in aspirations is a stunning yellow 993 RS. These days, RS-badged Porsches are a pretty outrageous affair, with wings, spoilers and bold graphics everywhere. Back in the mid-1990s, Porsche's most focused offering was a little more modest looking, with only a fixed rear spoiler, a subtly reworked front bumper, flared wheelarches and a pair of understated side skirts giving the RS game away.

The RS means business though. It has seam-welded body panels, thinner glass, no rear seats and an aluminium bonnet. Even the headlamp washers have been deleted in the interests of weight saving. Under the bonnet (or should that be boot?) is a bored-out 3.8-litre version of the classic air-cooled flat six that, with the help of Porsche's Variocam technology gets 300bhp at 6500rpm. That's 28bhp more than the standard car and enough to give the oh-so-yellow Porsche the ability to hit 173mph flat out, passing 60mph in 5.0secs dead along the way.

Helping to give the RS extra help in the twisties are thicker anti-roll bars, a ride height that's 30mm lower at the front and 40mm lower at the back, while cross-drilled and ventilated brake discs from the 993 Turbo find their way onto the RS.

Next up is the brutal-looking Silver GT2. Designed as a homologation special to allow Porsche to go sports car racing, The GT2 has a rear-drive chassis that's more or less identical to the RS's, but the same 3.6-litre turbocharged flat six found in the regular Turbo. Power is up 22bhp to 430bhp, though, courtesy of an ECU remap and boost pressure that's up by 0.1bar to 0.9bar.

Visually the bolt-on wheelarches and big spoiler leave you in no doubt as to the GT2's motorsport origins. Inside, there's also precious little in the way of creature comforts, but you do get the full He-Man roll cage, pukka racing buckets and six-point harnesses.

Third in our trio of 993s is a rather unique GT2-look Turbo. Its owner has put a simply stunning amount of work into it, including replacing the roof with a non-sunroof item (standard 993 Turbos have apparently been known to flip their lids at high speeds). While the roof was off an integral roll cage was inserted into the shell. The car has also had carbon fibre doors and bonnet fitted.

But it's under the bonnet where the really interesting changes have occurred. The headline news is that the original turbos have been replaced with a pair of KKK K24/26 and the fact that the car spent four months with Porsche engine guru Rheinhold Schmirler to create the current state of tune. The list of other modifications runs into next week, but suffice it to say that the result is 580bhp, 587lb ft and an ability to hit 300kph (186mph) form rest in 38.9secs.

Closet power fiend that I am, I go for the heavily modified Turbo first. For a car that has had £185k spent on it, the Turbo initially feels somewhat less extravagant than you'd imagine. As we trundle through the Malton traffic only the super-sharp clutch and the occasional shop-window glimpse of the GT2 bodykit and outrageous wheels give the game away that this is a rather special Porsche.

We soon get out on to clear country roads, though, and the Turbo reveals its true colours. This, truly, is a savagely fast machine. In its original form, a 993 Turbo could hit 60mph in just 3.7secs. That car had 408bhp. This one has 170bhp (a BMW 120i's worth) more.

But even the most impressive numbers wouldn't properly describe how this car feels. Driving fast, modern cars - as we do in this job most of the time - can easily desensitise you to speed, as modern engineers seem to prize linearity and ease of use above excitement. But step from a modern performance car - even something as rapid as a Nissan GT-R - into the blue 911 Turbo and you'd better be prepared for a shock.

Squeeze the throttle in second gear as you come out of a village and the twin KKK turbos take a breath before they fling the Porsche forward with enormous ferocity and you have to snatch the next gear more or less before you know what's happening.

In fact it would surely be hard to keep your licence if you had your name on the V5. There was one particular right-hand bend on a bridge that was part of our test route and, well, put it this way - I thought I was approaching it at 120kph before Pete pointed out that, er, the speedometer was calibrated in mph not kph...

Manically fast though it is, the Turbo is surprisingly usable on the road, with a relatively comfortable ride, massively confidence-inspiring brakes and the general sort of adjustability that you would expect of a much less focused car.

The silver GT2 isn't quite so approachable. For a start it's not exactly the work of a moment to clamber over the exposed roll-cage, drop yourself into the hip-squeezing bucket seats and clip up the six-point harness, even if it feels pretty snug and special once you're in. Then you're faced with a super-heavy clutch and brakes that squeak in the most embarrassing way.

Get the GT2 out on to the open road and it neither feels as fast as the blue Turbo, nor as comfortable over rough roads - this is a car that was nicknamed the Widowmaker and you can well believe it. This is not the sort of car to suffer fools. No doubt on a track its stiff suspension and solid-but-sharp steering would make the GT2 absolutely epic, but on everyday roads and in everyday conditions the Turbo comfortably has the measure of it. Stunning though it is, the silver monster is a car for high days and holidays only.

Which leaves the RS. With just 300bhp and a far more ordinary interior than the two other monsters, the yellow RS could be forgiven for feeling a little over-awed (in as much as an inanimate object can feel anything).

But the lightweight, pared-down naturally aspirated 993 RS is a much more pure expression of the core 911 values. It's fast enough to keep you amused, but straight-line performance isn't its raison d'etre.

The RS is about that ultimate sense of feel. A sharp turn-in, feeling the weight of the flat six pushing you round a corner. The sense that you have to keep stirring the slick, accurate gearbox to get the best from the non-turbocharged engine.

In isolation, the RS is fantastic, but its party piece really has been improved upon by its successors - drive a new 911 GT3 RS and its pin-sharp handling will take your breath away.

By contrast, the adrenaline rush of the turbocharged twins is something that has been diluted, not increased, by their more modern counterparts. Of those two, the harsh, unforgiving GT2 is an awesome piece of kit but, for the astonishing way it manages to mix everyday driveability with the kind of adrenalin rush that ought to be illegal, the 580bhp 911 turbo is in a class of its own.

As a driving experience it is utterly unique and, for me, truly deserves the title of 'ultimate 993'. It's a shame there's only one of them.