Pumping out a gargantuan 475bhp makes this the most fearsome Cobra replica we've had the stomach churning pleasure of piloting.  Stent gathers together his rather pummelled thoughts!

Performance figures, don't you just love them? Instantly impress your friends by reeling off a series of figures that mean your car's faster than theirs. But whether its a 2 litre Pinto that's struggling to make 115bhp when it's supposed to be a 175bhp screamer, or a 200bhp Rover V8 that is actually pumping out an asthmatic 140bhp, reality is often rather more mundane. And the more supposed power on tap the larger the differential can often be. 350bhp turns out nearer 220bhp and so the story goes on.

In fact, such seems to be the discrepancy with most quoted figures that only a handful of cars we've tested really seem to deliver the goods. 270bhp from the Westfield SEiGHT John Eales prepared Rover V8 took the diminutive master blaster to a record beating 60mph in just 3.45 seconds no questions asked there! And DJ Sportscars' Cosworth powered Rush must surely pump out its claimed 350bhp when the turbo is at full tilt it's terrifyingly quick. Of the big cars, Southern Roadcraft's old Chevy powered demo car was said to be good for 350bhp and was unquestionably the fastest Cobra replica we've ever got our hands on brutal, angry power that melted rear tyres for breakfast. Serious respect due to all these memorable performers.

Like Southern Roadcraft's mean mother, the Gardner Douglas we've recently tested was also jet black, but the power produced by this one made the SR V8 look a pale shade of grey by comparison. The tweaked Chevy has been dyno tested to a confirmed 475bhp with no less than 460ft/lbs of torque for good measure. This one's the Tyrannosaurus Rex of Jurassic Park and it hasn't eaten for a month! Be afraid, be very damn blinkin' seriously terrified.

Gardner Douglas built this GD427 for a customer as a road car with the potential for occasional weekend sprint events or similar. From the very outset, the mechanical specification was to be of primary importance with bodywork details and other frills coming second. As such the car is still in its extremely impressive gelcoat colour finish really first rate. Lexan shatterproof wind deflectors take the place of any fancy windscreen and the interior is kept a tasteful shade of black.

So, no frills on the outside, but a real box of tricks underneath. GD's much respected backbone chassis is in standard form and bracketed for the company's upmarket 'Euro' spec suspension. Whilst GD's standard Jaguar based car is more than adequate for most builders, the 'Euro' package offers a substantially reduced unsprung weight combined with the ability for almost unlimited tweaking of braking components and much greater tuning potential for the suspension geometry. Essentially, we're talking purpose built for the job rather than raided from someone else's parts bin.

Double wishbones at each corner are linked by GD's own cast alloy uprights which would normally make use of Granada Scorpio Cosworth discs, calipers, hub assemblies and rear differential. On this particular car the rears are standard vented items while the fronts nave been changed to 12 " vented and slotted discs with Alcon 4 pot calipers and Mintex pads. When customers are heading for a serious power unit, GD also recommends changing the rear differential back to the beefier Jaguar item. The V8 engine, as you might have guessed, is a little bit special. Built by Engine Data Analysis, of Castleford, it started life as a Chevy 350ci which was immediately stroked out to 383ci. Brodex alloy heads replaced the original steel items, street spec roller cam lifters and timing gear make the most of a special cam designed to deliver smooth road manners as well as serious power. Fully blueprinted and balanced, the new unit is fed by a 750cfm Holley double pumper carb and has too many other mods to mention. The result of all this work is, as I've already hinted at, extremely effective and we should jolly well hope so with an outlay of some £10,000!

But the fun doesn't stop there because the gearbox makes suitably impressive reading too. It's a Borg Warner T56 6 speed gearbox as found in the humungous Dodge Viper. Many of you may recall that gearing in this V10 powered giant is on the high side and, combined with the Jag diff, in the GD427 it produces almost comical statistics. If the engine could pull maximum revs (7500rpm) in top gear (which of course it couldn't due to its aerodynamics) you'd be travelling at some 275mph! At more understandable figures it means you're ticking over at just over 2000rpm when travelling at 100 miles per hour. Gardner Douglas originally fitted a 160mph speedo in the car but the owner has already broken that so it has recently been refitted with a 200mph one break that if you dare!

Gardner Douglas has always been a fan of the underslung exhaust and the company has the fitment down to a fine art. In this case the main bore was enlarged to 3" with the tailpipes coming out of the main silencers enlarged to 4" and including further silencing down half of their length The result is hardly subtle but neither is it hugely offensive in the way some side pipes can be.

To keep all the available power somewhere near the tarmac, GD has fitted some serious 255x45x17 Yokohama AVS rear tyres onto some Image 17" Halibrand replica wheels (235x45x17 at the front). Filling the wheelarches to the brim, they certainly make the GD427 look the business and combined with the wind deflectors, black side vents and generally mean looking finish to this car you can't help but be impressed. And we should return to that black bodywork for a moment as it, rather like the underpinnings, is surprisingly different. Whilst it is already largely unique in the Cobra replica world by being a semi monocoque structure, this particular shell also has a unique construction, which further reduces weight (by an impressive 70lbs) and increases tensile strength.

The Gardner Douglas Cobra replica has always been a bit different from the rest of the fake snakes. The backbone chassis is often a talking point, as is the smoother and more slender looking bodywork, but there are also innumerable smaller differences that you only notice when getting a little closer. Whilst there's nothing to stop you using external bonnet catches, GD has always leaned towards a more conventional under bonnet release which gives the outside a cleaner and perhaps more legal appearance (the external catches are extremely unlikely to comply with external protrusions regulations).

But even smaller things, like opening the doors, are made slightly different in the GD.  Instead of the usual door latch and release mechanism at the back of the door, GD fits a beautifully turned­-up door handle towards the front of the door with an internal mechanism back to a conventional catch. Not a major point, you may think, but it makes opening the door when seated that much easier and has a considerably higher quality feel than the more familiar set up.

GD's own seats look extremely smart and feel solid and well made. A headrest pinched from a Fiesta and retrimmed also makes a nice change and looks spot on. The customer for this particular car is well over six feet tall and GD therefore fitted its extended footwell option which sets the pedals further away from the driver. The headrests actually limit how far the seats can go back and when the customer uses the car he removes the driver's headrest which allows the seat to run back a further inch or so.

A Raid leather steering wheel looks and feels terrific and has been fitted with a Snap Off hub which, as the name suggests, allows the wheel to be instantly removed for security. The pedals are slightly offset to the side in the GD but it's something you quickly become familiar with. The seats in this car only have a half foam base section which means you sit well down in the cockpit and the serious four­ point harnesses with quick release centre catches also take some getting used to. But everything else is pretty much as you'd expect. The standard trim kit looks smart and tidy while the dash on this car has been slightly modified to give it a more traditional look. The standard item would normally sweep down in the centre to meet the tunnel but this one has a more original 'cut off' look.

To retain the steering lock you obviously have to retain the original ignition switch, which means reaching under the dash and fishing around until you find the key. Turn that and then press the button in the centre of the dash for some major action. The clutch may not be exactly light, nor is the steering at slow speeds (a combination of the relatively small steering wheel, GD's quick rack (2.5 turns lock to lock) and the larger than standard front tyres), but once on the move none of these cause much further thought.

What is immediately impressive is the fantastic gearchange. On big cars with serious power and hefty gearboxes the changes can often be extremely cumbersome and occasionally downright awkward. Not so here. The Viper 'box is a dream snicking through the gates with a smooth and precise action. With an extra cog to deal with one might easily expect the gears to be tremendously close together, making it difficult for the driver to always select the one he wants. Instead, this box of tricks has just the right weight and springing to ensure you're spot on every time. It's a great confidence booster when you're dealing with an engine as potentially hairy as this.

With 475bhp on tap it would take a brave or psychotic man to get stuck in straight away, so the first few miles are taken steady while you get used to the feel of the car and the delivery of umph from under the bonnet. Despite the humungous power, from the very outset the customer had wanted the whole lot to be manageable in traffic, and in these early stages one appreciates the effort that must have gone into this engine in order to achieve such a fine balance. With great gobfuls of torque available in any gear and at any revs it's easy to settle down in fourth or even fifth gear and potter through town and around the lanes. But you're not reading this to hear me talk about pottering. What's it like when you put your foot down?

Gardner Douglas' main man, Andy Burrows, drove me to the photo location and pulled out a few stops when the road permitted. In a straight line and from a virtual standstill the acceleration, noise and general aura of terror is mind numbing. My four point harness is already done up tight but first gear squeezes me back into the seat with such force that the straps momentarily feel loose. I can barely keep my head upright and resort to leaving the headrest to do the work that my neck muscles are so hopelessly failing to achieve. First is over in a flash; a violent hammer blow of acceleration that is finished before it has started. Second follows in much the same way, third isn't much different but Andy is already changing up early. On the track he's pulled over 130mph in third with another three cogs still to go! Breaking a 160mph speedo now seems only a mere formality. Just a question of when rather than if.

Adding to all the fun is the lack of any sensible windscreen. Even at reasonably mundane speeds the wind is pummelling my head, testing my hair root structure to the limit and, quite frankly, making a mess of my glasses. They're rattling around on my nose like I'm on a fairground roller coaster and as we nudge three figures I'm seeing seventeen different roads ahead and not one looks like going in the direction we're travelling. Such was the beating that my glasses fell apart the next day. The screws had simply rattled loose. They weren't built for this sort of punishment and had decided that enough was enough!

And it's not just in a straight line where the GD is impressive. Andy's racing experience and familiarity with the local roads means he's chucking the car around like a go-kart. The GD427's handling has always been impressive and it's the reason the company took a race prepared car into the BRSCC Historic Replica series. To prove the point the car has just won the series with a further two races still to go. Out here in the lanes it's also doing the business screaming around corners at speeds you'd struggle to match in a small roadster.

But now it's my turn. As I begin to push on a bit that once heavy steering becomes precise and communicative. Almost too much so, as the car seems to have a tendency for follow back road undulations and you find yourself having to keep a firm hold on the action. That's probably largely due to the quick rack fitted to this car and the more standard one (3.5 turns lock to lock) might be a little more forgiving on back road blasts. That said, once you're used to it the rapid response of this set up is pretty addictive.

The medium weight clutch was something you quickly got used to and found well balanced for the power on tap and the serious gearbox. Older Gardner Douglas cars used to run with a servo but Andy has now done away with that in favour of a more responsive brake feel. With this car there's certainly massive stopping potential and a firm shove gets the anchors on in confident fashion. With the huge Alcon front discs we'd be surprised if brake fade was ever a problem and it certainly wasn't evident on our road sortie.

As we've found in the past, it's the ride of the GD Euro cars that impresses us most. With its huge 17" alloys and 45 profile tyres you'd expect a pretty rattley journey. What's more, this car has been set up slightly firmer than normal to help maintain top speed stability and maximum agility for its occasional competition use - not something you'd expect to work well on typical British back roads. In fairness it probably is a little on the firm side but harsh is certainly not a word that comes to mind. This is a ride you could live with easily. There is no jarring or crashing over the bumps and such is the positive feedback and level cornering attitude that one would forgive something considerably harsher.

The way the suspension deals with such huge amounts of power is also extremely impressive. From a standstill it comes as little surprise that you can break rear tyre traction, but even here it is only for a second. In almost any other situation you'd have to be pretty clumsy and extremely lead footed to get any sort of breakaway. The GD427 simply locks in and goes. Even when you're utterly prepared, the force of full acceleration in second gear is extraordinary. It's simply huge, brutal power that wallops you into the back of the seat and makes you feel like the car's about to take off. In fact, such is the G force that the standard seat runners are struggling to hold the seat in position. When you're really pushing on they simply give up and you suddenly find the seat shooting back an inch or so onto the rear bulkhead. The company's just about to change them for some beefier items as the effect is hardly desirable at such critical moments!

As the corners approach it's anchors on the brakes and power on through. Whilst the GD is obviously a big car and fills the road it doesn't behave like one, instead remaining positive and alive through the corners. In our short encounter one could only just begin to get an impression of the car's full potential, but there was little doubting its ability. This is a Cobra replica that thinks it's a Westfield.

Perhaps it was a blessing in disguise, because the wind deflectors really don't do an awful lot and therefore limited the speed you could travel without the aid of a helmet. Just nudging three figures was about tops without my already shaky glasses collapsing on the spot. The Lexan screens are the Mark 1 versions and Andy has been playing around with bits of card to see just where they need to be changed in order to improve their efficiency. A full width version may even be given a trial and would surely look quite amazing.

Using all new parts, this car was built up by the company to the customer's specific requirements. With around £10,000 worth of engine alone you'll have guessed that this phenomenal machine is hardly cheap. In fact, £32,000 + VAT is what you'd be looking at for something similar. However, put in perspective and considering what this GD427 will do, the price doesn't seem quite as huge as one might have expected. Using a more standard Chevy engine and building the car yourself, Andy reckons most Euro builders will be spending nearer £18,000 20,000.

Such high spec underpinnings are never going to be cheap and for those on a tighter budget the Jaguar based car comes in at a more manageable £12,000 - 14,000.  Some customers have even managed to bring that down to £10,000 but we're talking about a reasonable Chevy powered car with decent interior trim and proper spec wheels and tyres. All of which puts the Gardner Douglas firmly in the running as a major player in the affordable Cobra market. As for the Euro spec car, that's something very special indeed.

We were also impressed by what appeared to be a great back­up service by the company. Not only can Gardner Douglas supply kits to almost any stage of completion but the company's twin build videos (£26.50 inc. p&p) really seem to take you through the typical build scenario in great detail. They're professionally put together and immediately show you twice as much as you'll ever get from a build manual. They are supported by some brief build notes which will keep you on track, but the videos really show the way forward for other companies. Another nice feature that more and more companies offer these days is a comprehensive post build check-up. This should give you great confidence that everything is as it should be after your long efforts putting the thing together.

Just settling into some smart new buildings, Gardner Douglas has the feel of a well-established company with a healthy order book.

A comprehensive brochure pack is a worthy investment and can be yours by sending £3 to Gardner Douglas Sports Cars, Pinfold Lane, Bottesford, Nottingham NG13 0AR  Tel: 01949 843299. Alternatively, fill out the Brochure Request Form.