I reckon the man from TechArt is the bravest guy on the planet. Imagine this: you’re him and you meet a stranger at Stuttgart airport, somebody you’ve never seen before and know nothing about. Then you hand him the keys to a Porsche 911 GT2 that has been tuned by your company to a quite astonishing 690bhp — a nice round 700PS in Euro-speak. Then, as the stranger asks if there’s an autobahn nearby, free from constraints as tedious as a speed limit, you sit him behind the steering wheel and climb into the passenger seat. And then it rains.

The TechArt GTstreet RS is without doubt one of the maddest cars on the road. A quick squint at the RS’s specification sheet confirms this. Here is a car that takes as its basis the stratospherically capable 911 GT2, a ferocious piece of kit that already boasts 523bhp and a 0-62mph time of 3.7sec. TechArt then engineers it in order to boost its power by 167bhp and its torque up to 634lb ft.

TechArt is a little-known company based just outside of Porsche’s home town of Stuttgart, from where all production 911s emerge. And while it has no official connection to Porsche, TechArt has been tinkering with 911s (along with most other Porsche models) for more than 21 years. Strictly speaking, it is a tuning company, but that underplays what it does.

When I think “tuning company”, I get the image of somebody with an assortment of spanners strapping massive turbochargers onto somebody else’s highly developed sports car and hoping for the best.

Not these guys. TechArt has a 6,000-square-metre facility with the sort of engineering and design support you’d expect from a much more serious player. It designs and styles its own cosmetic modifications, such as spoilers, wings and sills, and then sticks them in a proper wind tunnel to make sure they work. And it will also do absolutely anything you want to a car’s interior, in any combination of leather, wood and the now ubiquitous carbon fibre.

The GTstreet RS has been fettled on all of those fronts. As well as the engine modifications, the RS gains a front-to-back cosmetic tickle, although TechArt insists that everything it does has a functional purpose. At the front, a new bonnet houses a deep valley at its leading edge, which vents air out to help suck the car to the ground, as well as providing extra cooling for the front-

mounted oil cooler. The RS’s front wings are TechArt’s own creation, too, with vents behind the wheelarch to exhaust hot air from the brakes. There are side sills, which feature an illuminated GTstreet badge when you open the door (a bit of bling I think it could do without). The thing that really draws attention, though, is the colossal rear wing. This isn’t as bad as it sounds, because, unlike most big-spoiler poseurs, this car can actually walk the walk.

That brings us to the firepower. Among other changes, bigger turbochargers, bigger inlet pipes, higher levels of boost and high-performance intercoolers have allowed TechArt to liberate all that extra thrust. And an uprated clutch has been added to cope with the massive forces at work.

The interior, titivated with stitching, embossed badges and bits of carbon fibre, is otherwise familiar 911 territory. The clutch feels initially a bit heavy, but as I trickle along urban roads, my first impression is of a car that feels remarkably friendly and easy to drive — my mother could handle this.

The RS also sports a manual six-speed gearbox with shortened shifts, which feels absolutely wonderful — direct, mechanical, just challenging enough to make things interesting (you do need to be accurate and firm).

A clear stretch of twisty B-road presents itself and a big bootful of throttle seems a good idea — maybe. Like the GT2, the RS is rear-drive only and has traction aids that can be switched off. I opt for “on” initially, to get the measure of the thing.

“Fast” doesn’t quite do it. This car’s performance delivery is vaguely psychic, as in “I think I’ll pass these three cars . . . oh look, I have”. And that big flat-six-cylinder motor generates a moaning wall of noise that sounds so refined and turbine-like that

you’re always surprised when the 7200rpm rev limit arrives. You need at least 3500rpm on the dial for the Star Trek warp-speed treatment, but once there, you’ll find the RS a staggering way to go cross-country. And the best news is that all that power hasn’t corrupted the standard GT2’s brilliant handling.

However, the really neat thing about the TechArt is that you can’t really tell where Porsche’s development stops and its starts — if Porsche was going to do a 690bhp GT2, I reckon this is pretty much what it would feel like. In fact, the car is so businesslike, unruffled and matter-of-fact in the way it goes down the road, even with traction aids off, that I find myself thinking, “Bet it could handle 1,000bhp.”

We finally find that bit of unlimited autobahn, along with the RS’s last party trick. Which is 180mph in the time it takes ordinary cars to get to 100mph, with all the stability of a plank nailed to the floor. With enough road, it’ll top out at 223mph, which is ludicrous.

And then the raindrops come and I discreetly reach for the traction control “on” button. There’s brave, and there’s foolhardy.

- Porsche carbon-ceramic brakes provide massive stopping power to match the RS’s performance

- Small winglets on the front bumper also generate some downforce, gluing the car to the road at 223mph

- The sports exhaust, with a flap-valve system, has two settings - loud and louder The engine cover is made of fibreglass - carbon fibre was deemed just too expensive, even for a car that costs £277,000

Hot Wheels specs

MODEL TechArt GTstreet RS
ENGINE 3600cc, six cylinders
POWER 690bhp @ 7000rpm
TORQUE 634lb ft @ 4500rpm
TRANSMISSION Six-speed manual
FUEL / CO2 22.6mpg / 298g/km
ACCELERATION 0-62mph: 3.4sec
TOP SPEED 223mph
PRICE £277,000
ROAD TAX BAND G (£400 a year)
VERDICT If you’re power-crazed and like 911s, this is it