Through two generations of MX-5 there has been a whole barrel of aftermarket conversions, from turbos to madcap V8s, aimed at upping the grunt factor of Mazda's charismatic sportster. But the guardians of the MX-5 flame at Hiroshima have never bought in to any of that stuff. Mazda's rationale, quite rightly, has been that balls-out speed and power are not what a car as simple, balanced and brilliantly communicative as the MX-5 is really all about.

Time moves on, though, and calls from Mazda America for more power to combat the likes of the Z4 and Beetle Cabriolet Turbo have finally tipped the balance. Hiroshima's answer is a light- pressure turbo version of the enduring 1839cc twin-cam engine, a conversion designed not so much to slash 0-60mph times and shred Tarmac but to fill out the torque curve and serve up stronger overtaking on A-roads and motorways.

So the bottom line is that the MX-5 Turbo delivers 170bhp at 6000rpm in Japanese tune, while torque jumps from 125lb ft to 154lb ft.

Despite that fairly modest upgrade, the turbo package also brings an uprated clutch and six-speed 'box internals, reinforced drive- and prop- shafts, plus a Torsen limited-slip differential and special exhaust.

The Turbo sits 10mm lower, gets Bilstein dampers, new spring and roll bar settings and wears slimline 17 x 7 alloys shod with 205/40 R17 rubber.

Opinion is divided on the coolness or otherwise of the Turbo's add-on spoilers, but inside the makeover is more gentle, with aluminium pedals, metal-effect centre console, silver instruments, and leather trim for the wheel, gearlever and handbrake.

First things first. Yes, the Turbo is fast, but again, read the small print. Mazda has engineered the conversion so as not to upset the famed 'oneness between horse and rider' feel of the MX-5. So the boost is smooth and linear, starting discreetly from 3000rpm. It's only when the engine has climbed to around the 5000rpm mark that the stronger top-end shove over the normally-aspirated 1.8 really starts to register.

At these kind of speeds the Turbo is comprehensively quicker than the unblown 1.8, delivering the kind of acceleration on full chat that can even have you backing off because you're suddenly entering a corner much quicker than you anticipated. This doesn't quite back-up the message about the Turbo being all about driveability, true, yet when you drive it hard, this is the impression that lingers.

The BP-ZET turbo engine revs to 6500rpm, a grand less than the normally-aspirated unit, and doesn't get the latest S-VT variable valve gear, either. With origins dating back to the old 323 Turbo days, Mazda's BP has never been the slickest four-cylinder engine on the block but it's a solid, effective player and now looking smarter than ever with its unique crackle red cam cover.

Clutch take-up on the Turbo is shorter and firmer than usual but the rifle-bolt action of the Mazda's six-speed 'box and pedal action are as precise and satisfying as ever.

The chassis mods and 17in tyres have tightened up the handling and brought a lot more roadholding into the equation. Again, against the standard 1.8, the Turbo can dive in deeper and corner much harder. For
a trackday car it would be great. However, there is a trade-off because when the rear breaks away it happens much more quickly too.

The MX-5 is still a marvellously darty little car, but in Turbo trim it's down a little on that legendary MX-5 involvement. Steering is not quite so telepathic and you don't feel part of the action in the same way. For all that, the Turbo's good, no question, but different.
It's a shame it won't be coming officially to the UK. Then again, with the next Ibuki-based MX-5 just a year away, some might perhaps see the Turbo as too little, too late. Still, for all those that have been panting at the gate for years for a factory turbo MX-5, your car is now ready.