As a result, the N does not merely use a lower and firmer variant of the i30's suspension: it sits on revised axles front and back, with completely recalibrated kinematics and the kind of costly adaptive dampers which aren't even an option on the cooking model. If you opt for the Performance version - which naturally we have - you get an electronically activated limited slip-diff, too, and 18-inch vented discs to go with Pirelli P-Zero rubber.
Nevertheless, the Leon's immediate advantage over the N is obvious enough: the current Cupra is remarkably good-looking in a way that doesn't need the supplementary body tinsel obligated by the i30's staid appearance - and, to a lesser degree, it's nicer inside, too. Again, this has much to do with the stock blueprint each hot hatch has to work from: the Seat is simply better reconciled and slightly more stylish (possessing the superior infotainment system does it no harm either). However - and this is a significant however - the N does come fully loaded and the Leon does not (there are nearly £2,500 worth of extras on our test car not including the six-speed DSG that pushes the standard price beyond £30k).
Twinned with the generally sleek shifting dual-clutch 'box, the benefit is obvious enough, too: the Cupra is express-grade brisk, especially in that burly mid-range way that makes a car feel mightily pleasing in the real-world. Inevitably there's some low ratio, front-axle scrabble to go with its extra potency, but it's rarely of the indecent sort. In fact, nothing the Leon does could be called indecent: it's as rounded as a squash ball and agreeably capable of accelerating like one.
Hyundai agrees that the N is almost half a second slower than its automatic rival to 62mph, although it's at middling revs (away from the obviously quicker upshifts) that the difference really plays out. The new division has worked wonders with its parent's run-of-the-mill 2.0-litre Theta petrol engine - but only so much is possible, and beneath the obviously heightened gruntiness that comes with a bigger turbocharger, there's still a stock unit not built to rev with much vigour. In isolation it's fine; being driven back to back against the EA888's fast-spinning thrust does it no favours, though - and there are times in the latter cogs when you sometimes notice how long you're waiting for the shift lights to ignite.
The real distinction, though, lies in the forthright character of the trick chassis. Where the engineers - or, even more feasibly, the executives who sign off the engineers' work - might have diplomatically opted for a tentative sort of hot hatch (i.e. one as inoffensive and as benign as the underlying i30) the firm has instead collectively taken hold of the 'proper' knob, and knowingly cranked it around to about an 8.
Naturally there is a dynamic pay-off for all this single-mindedness: the N's obvious vertical stiffness occasionally degrading into the kind of downright abruptness that has your head incessantly nodding - but it doesn't take long to appreciate that while the wick may have been turned up, Hyundai has not wholly jettisoned its commitment to refinement. Stiffer it may very well be, but compared to the rather airy Leon, the car's running gear is as muffled as a diver's watch.
Where the Cupra starts to faintly toil under shifting weight, the much tauter N hunkers down into the kind of flat- and phat-bodied posture which has you attacking fast corners with genuine, suck-it-and-see relish. True - the steering response isn't quite up to the same level of feedback as the messages filtering up the seat backs (the Leon's rack attains weight much more convincingly) but it is easily astute enough to have you threading corners together with the kind of moreish enthusiasm that all well-sorted hot hatches tend to indulge.
Certainly you'll want to avoid the N mode, that - on British roads - immediately curdles the fun with the kind of try-hard chassis tune that virtually forfeits decent road manners on standard 19-inch alloys. But keep the car in 'normal' (or single out the right option for each component) and the compromise seems neatly struck - not least for the nicely balanced, line-tightening way it comes unstuck when provoked.
The Leon is less interested in the possibilities afforded by lifting-off mid-corner - although its claim to superior all-rounder status is hard to refute. Undeniably it has the better, keener and quicker engine, finer looks and the sort of (adaptive) suspension setup which doesn't try your patience when you've inevitably flicked back into commuter mode.
The car they have produced is quite unlike any other current Hyundai, and easily the best among them. It's better than the Cupra, too - not in every way perhaps and certainly not for every purpose - but better where it counts. If that's destined to be the N division way, the tuner is already halfway to the only reputation that matters.
Inspired? Buy a SEAT Leon Cupra here
SPECIFICATION - HYUNDAI I30N PERFORMANCE PACKAGE
Engine: 1,998cc 4-cyl turbo
Transmission: 6-speed manual, front-wheel drive (limited-slip differential with Performance Package)
Power (hp): 275@6,000rpm
Torque (lb ft): 260@1,500-4,700rpm
Top speed: 155mph
Price: £27,995 (all options included)
SEAT LEON CUPRA 300
Engine: 1,984cc, 4-cyl turbocharged
Transmission: 6-speed DSG, front-wheel drive
Power (hp): 300@5,500-6,400rpm
Torque (lb ft): 280@1,800-5,500rpm
Top speed: 155mph
Weight: 1,421kg ('in running condition with driver')
MPG: 41.5 (NEDC combined)
Price: £31,805 (As tested £34,280 comprised of £575 for metallic mystery blue, £440 for navigation system high, £265 for SEAT sound system, £610 for Comfort and driving pack 2, £460 for Keyless entry and go and £125 for Safety pack)