A Mustang is never going to be shy and retiring, especially one with a 5.0-litre V8 under the bonnet. But what’s it like when you bolt a supercharger on and unleash 670hp through the rear wheels? Deceptive, in a word.

 

You notice the Performance Shifter Kit first, the stumpy little lever reducing the throw by nearly a fifth over the standard set-up. And the motivation to get a bit Fast and Furious (or should that be Bullitt?) with your gearchanges is that bit stronger thanks to your more intimate physical connection to the big V8. Straight away this Mustang significantly more butch than a standard one. Which is kind of appropriate.

My first run in the car is around Goodwood’s famously fast and unforgiving circuit, the combination of 670hp, a damp surface and little more than a few metres of wet grass between track and tyrewall offering food for thought when the speeds are well into three figures. This car is louder thanks to its 2.5-inch cat-back exhaust system, also from Ford Performance Parts and supplied under licence from Borla. And to begin with the extra V8 soundtrack is enough to convince me I’m making good use of the extra power. Turns out I’ve been a complete wuss though.

 

As I complete my lap and exit the chicane I give the accelerator a proper shove. Holy moly. Unlike a turbocharger’s whizz-bang spool-up there’s no sudden kick in the back, meaning on gentle throttle openings it feels like a standard 5.0. But when you floor it the needles on the rev counter and speedo move so quickly they become blurred, much like the scenery outside. And the speed with which it rips through the gears mean you’re kept very busy with that short-throw shifter.

My instructor is giggling at my stream of expletives and the panic braking as I charge headlong into the first corner. Thankfully the standard-fit six-pot Brembos feel up to the job, likewise the stock GT suspension. I’d expected the car to be a bit of a handful but, for all its monstrous power output, it’s pretty civilised. Almost like it was built for it all along in fact.

 

I’m still mindful of the damp looking track but much more confident of the Mustang’s ability to deal with it. As the heart-in-mouth right-hander at Fordwater approaches I’m ready to slot fifth and get on it. And where the standard GT can feel a little breathless the supercharger gives it instant throttle response at any speed or revs. It’s a Ford Performance Parts kit based on the Roush Phase 1 package sold in the States and includes an Eaton 2.3-litre Twin Vortices Series (TVS) supercharger, high-flow inlet and outlet ports, new intake manifold, twin 60mm throttle body system, fuel rails and injectors and intercooler system. The performance it unleashes is absolutely addictive, the interaction with the manual transmission meaning it’s a car that needs to be driven properly to be enjoyed.

 

As driven this car is just shy of £54,000, the supercharger kit nearly ten grand on its own. But the parts are all available through your Ford dealership and warranty friendly. And you’ve got four grand and an extra 240hp in your pocket to dent the smugness of any BMW M4 drivers you might encounter.

 

Given the track environment and experience with the US-only GT350 R comparisons are inevitable. The Shelby is probably more suited to handing the BMW (and plenty of others) its ass on a circuit thanks to its reduced weight, more exotic engine, Cup tyres and specially tuned suspension. I’ve been lucky enough to sample the GT350 R for a couple of laps previously and it’s a much more sophisticated machine, this supercharged 5.0 GT more blunt instrument than precision weapon.

 

No less charming or exciting for that though. And as the catalogue of officially approved parts permits further tuning and personalisation within the comfort of your factory warranty it’s nice to know Ford can help you put the muscle into your muscle car. Just the right side of unruly, this is the Mustang showing its true red, white and blue colours.

 

Read the full feature in the September 2018 issue…