Walkinshaw W507 2015 Review

Not the polite 12-year-old who minded his Ps and Qs, but the cheeky kid who would scrape together sparklers and matchsticks in the backyard shed and cram them into an empty dunny roll to be lobbed into the next-door neighbour's yard...

Yep, this Walkie is disruptive, but in all the right ways.

Before I've driven a kilometre along an unusually quiet Punt Road in Melbourne I get the foreboding feeling this car will get me in trouble... Despite being a family man, a responsible adult and a decent member of society, part of me is secretly rejoicing as I involuntarily revert to a mentality long since passed – one that celebrated excess.

Sitting at a set of traffic lights, my foot rests on the accelerator and I can feel the cadenced beat of the V8 – in fact it's felt through the seat, such is the resonance – and with just the lightest touch as the lights go green the lumpy idle smartens up and turns into melodic purr that even at 40km/h stirs the soul.

Not everyone was stoked with the sound; some said the car was too loud for them, but each to their own. Me? No dramas at all. I noticed the drone of the exhaust driving solo but wasn't offended and conversation while cruising down the freeway for 40 minutes with two others on board certainly wasn't strained.

It's not just the ceramic coated headers, catalytic converters, cold-air intake and dual cat-back exhausts that make this car special. Yes, the noise is exhilarating but when you lump in a new supercharger pulley upgrade kit and a judiciously calibrated ECU map (of 40 different tunes were tested, with the help of 20 GTS owners), the result is seismic.

Walkinshaw was never going to be rushed, despite the high uptake of the vehicle required for this $7990 package, the $94,490 HSV GTS. Instead the company took its time, involving current GTS owners to provide crucial feedback in order to refine the vehicle's temperament, from its power delivery to overrun crackle on a trailing throttle. Fifteen months later and it's done.

As I sit at another traffic light, this one a gateway to a more intriguing 80km/h limit, I'm tempted to nail it. The temptation is realised and I'm surprised at how linear the power delivery is. There's scads of torque low down, enough to overpower the chubby 275/35-seris Continental tyres shod to 20-inch diameter, 9.5-inch wide rear rims.

But modulating that power via the loud pedal so as to maintain traction comes naturally, and this is where Walkinshaw's 25 years of experience comes to the fore.

Despite the massive power, this Walkinshaw is easy to drive – something that can't be said for some high-output sports cars. I commute to work on two occasions and travel through the guts of the city and the powertrain doesn't put a foot wrong, the car behaving predictably and reliably. While big numbers are a must, Walkinshaw insists refinement is something it strives for in its kits, and this W507 is one of its smoothest yet.

It doesn't have the wild nature of the W497 either, which has 105Nm more torque again – for 955Nm – and feels very confident and communicative through corners, under brakes and at full noise. As a donor car, the HSV GTS is better equipped to deal with the high power loads than the W497's HSV ClubSport, with a (slightly) more sophisticated chassis.

Power has been ramped up from the regular HSV GTS's 430kW to 507 (hence the name), while torque is hiked 110Nm to 850. In layman's terms, it's enough power to take on an entrenched political party, and generates enough heat to flash fry a buffalo on the cylinder heads. That said, cooling was never an issue, even in stop-start traffic on a 30-degree day.

Oh, and it's fast.

Paired with the six-speed auto the Walkie hits 100km/h in 4.3 seconds (as tested), seven-tenths of a second faster than the last GTS we sampled.

Peak power and torque arrives 50 and 550rpm higher (507kW at 6200rpm and 850Nm at 4400rpm) than the GTS, and for the record conditions were mild during testing: 24 degrees, clear skies, light winds and a fresh set of Continental boots.

The perfect launch requires about half throttle, but once rolling it's power time. Feed it on fast and over 4000rpm the W507's battle cry is pure lunacy – an utterly brilliant wail equal parts V8 exhaust bellow and supercharger whine. At full noise the W507 sounds like million dollar military hardware.

The car sprints forward effortlessly from low revs but there's so much power on tap it takes extreme self-discipline not to smoke up the rear heaps each and every time. And if that's the appetiser, then the entrée is an even beefier midrange. But the main course is the car's top-end, which is just unbelievable [Ed: Check out the video soon].

The Walkinshaw-tuned HSV GTS doesn't truly feel like it's nearing its zenith until you reach 5000rpm, and at which point the supercharger whine is mental, adding jet fighter element to proceedings that'll leave onlookers wide-eyed in disbelief. The way the Walkie's top-end functions is almost race car-like, such is its predilection to suck down ever larger quantities of air as the supercharger screams for more.

Naturally the W507's 680hp output means it's not going to rival a Toyota Prius in terms of fuel efficiency. At 100km/h in top gear, the car rarely drops below 10.0L/100km but I'm pretty happy with a combined figure of just over 15 litres at the end of our four-day test.

For owners of high-performance Australian sedans, Commodores and Falcons, there's a veritable smorgasbord of aftermarket tuning groups eager to work their magic on the home-grown rear-drive machines. But there are few who have the pedigree of Walkinshaw Performance Products, and even fewer who honour existing owners' driveline warranties after the fettling is complete.

As I drive the car back to Walkinshaw HQ, I realise it's not every day an Aussie car comes along with the same combined output as eight Toyota Yaris', and although the price of admission to a GTS is not insignificant, at almost $100,000, it means that the W507 corners and stops just as well as the donor car.

In other words, very nicely, thank you very much. It maintains a good attitude in turns and can be rewarding on a fast, winding road. Yep, it's far more than just a straight-line missile.

And despite its ludicrous power output, "arrest-me-now" looks and "get-outta-my-way" acoustics, I didn't get into trouble once, yet still felt as excited as a kid with a fist full of fireworks and a zippo lighter.

And don't expect Walkinshaw to rest on its laurels, either. WPP's general manager, Tony Harris, said there's "absolutely" scope for more power.

"This is the first phase," Harris enthused. "If there's demand we could do more, the potential is there."

As the saying goes, too much of a good thing is never enough…