Just what is Mountune’s M235 upgrade for the revered Mk8 Fiesta really like?

Words Jamie  /  Photos David moore 

Just over a year ago, I drove Mountune’s first upgrade for the Mk8 Fiesta ST. I remember it well – the car was the centre of attention at Mountune’s Cars and Coffee meet as it launched the company’s new SMARTflash system, where you can literally remap the car using your phone.

But it wasn’t just the technology that impressed me – with the software installed, it was an absolute hoot to chuck around the B-roads and local countryside.

Well here I am again, about to drive the very same car some 15 months later. And you don’t need me to tell you that a lot can happen in the world of tuning in just over a year. The previous m225 package has now been superseded by the new m235 upgrade instead. It retains the same alloy airbox and performance filter but Mountune engineers have made a few tweaks here and there, and the result is slightly more power and more torque – now up to 232bhp and 258lb.ft. 

That increase in peak figures wasn’t the main objective behind the m235 update, though. Instead, Mountune’s goal was to make the Mk8 ST driving experience even more fun. 

In the last year or so the company has been busy developing a whole range of performance upgrades for the Mk8 ST to accompany its software, and this car – the demo/development mule – has been fitted with many of the latest offerings. Not all are available to customers just yet, but the car I’m driving is fitted with the m235 calibration and induction kit, a high-flow induction hose, a high-flow turbo elbow, a short-shifter kit, a performance intercooler, a development oil cooler, six-pot 302mm big brake kit, and a set of sports springs that are also in development. So, what difference had that lot made since I last tried this car?

Quite a lot, actually. Let’s start with the new m235 software. On a dyno graph it perhaps doesn’t show much difference over the old m225, but you don’t drive a car on a dyno. Behind the wheel, it really shows. 

The Fiesta feels even more eager than before, and the mid-range kick in the backside seems more potent. It still retains that playfulness and keenness to rev but feels a little sharper all round with seemingly quicker acceleration too. I’m comparing from memory and I can feel the difference, so if you jumped out of an m225 and straight into the m235 the difference would be even more apparent. 

Of course, the latest goodies such as flat-shift and enhanced exhaust sound (with even more aggressive pops and crackles on the overrun) are welcome additions too, while the OEM levels of smoothness and refinement are evident no matter how badly you mistreat the poor thing on the fast, flowing country roads. 

Out on the motorway, as before, the m235’s lack of ultimate outright horsepower does show when compared to an RS, Mustang, or the m330 Focus I recently tested. But don’t forget this a tiny 1.5-litre three-cylinder, so to even be thinking in those terms shows just brilliant this little EcoBoost is.

The m235 software is not all this car has fitted, though. Driving demo cars like this, mid-way through the development process, makes you appreciate just how much effort Mountune puts into the performance hardware. Everything is designed to work together as one cohesive package, and you can feel it behind the wheel. 

The intercooler and high-flow induction hose and turbo elbow have all been designed to work in harmony to provide a smooth, unobstructed route for the incoming air, while the oil cooler is there to ensure the critical temps are kept stable and to prevent the clever ECU from dialling back any of that precious power for fear of safety concerns.

Some of the biggest improvements for me, though, are the sports springs. Not only does the Mk8 ST look a million times better by dropping it closer to the floor, with Mountune’s springs fitted it handles direction changes much better, and actually rides more comfortably too. On the twisty country roads you can really exploit the nimble chassis, and while I can’t make it a cock a wheel for any of the photos you just know this Mk8 hasn’t lost that trademark Fiesta handling trait. Coupled with the six-pot brakes, which use a sensible 302mm disc that aren’t so massive you need specialist new alloys to fit over them, these two upgrades alone make a massive transformation to how you drive a Mk8 Fiesta.


I always think tuning a car should be a journey – something that happens over time, with small incremental changes making notable improvements at each step, Yes, of course you can opt for an all-at-once approach for maximum impact, but to me that’s a bit of a one-hit-wonder. Once you get used to it all there’s nothing more to come. Not to mention it can be prohibitively expensive to add everything at once.

Instead, making updates as you go allows you to really appreciate and understand each improvement at every step. And thanks to the way Mountune develops and tests its products, you can be sure that each upgrade you make will work in perfect harmony with the rest of the car. 

This is a car that still has plenty more to offer, and the future is looking very bright for Mk8 ST owners.  



01277 226666




Kelsey Media Ltd
The Granary, Downs Court
Yalding Hil, Yalding
Kent, ME18 6AL
01959 541444

© 2021 Kelsey Media Ltd