Starting in 2004, Unitronic has offered owners of Volkswagen and Audi vehicles a host of staged software and hardware performance modifications that focus on tuning engine and transmission calibrations for higher output, quicker shifts, and better overall response. The company claims its products allow tuners to maintain OEM-like reliability and driveability in their cars while also maximizing performance.
But as we've seen with tuner cars in the past, the disparity between the marketing line and how modifications behave on the road can be vast. So when the opportunity came up to get some seat time behind the wheel of this MK6 GTI—which sports Unitronic's full lineup of powertrain modifications—we jumped at the chance. Some seat time on canyon roads gave us the opportunity to see how the tuning company's products hold up in the real world. Subsequently, we also discovered that this particular car belongs to Alex Keyes, a professional racer who competes in Red Bull Global RallyCross series, which only sweetened the deal that much more.
"I've actually had this GTI for a few years now and for most of time I've owned it, I've just been driving it around stock," Keyes says. "I've always liked driving more than working on cars, but eventually I got bored and wanted to learn how to work on it and what could be done. I blew the original engine in the car back in December and had decided by January that I might as well build up the new motor since it was outside of the warranty. What I love about the GTI is how much power you can get from software like the Unitronic Stage 2 tune and how well it responds to chassis upgrades as well. With a little bit of love, they are extremely capable cars."
"We wanted to show our customers what can be achieved with this car and our performance products when it's put in the hands of a professional," says Alexandre Guilbault, director of product development for Unitronic. "Alex's background in the GRC series was a natural fit for the project."
While Alex's GTI sports chassis upgrades that include BC Racing BR series coilovers, a Whiteline 24mm antiroll bar, and a Whiteline front control arm anti-lift kit, the powertrain tweaks come exclusively from Unitronic. "The Stage 2 ECU performance software was my initial, basic plan for my MK6 GTI," Keyes says. "However, after getting a look at Unitronic's Stage 2 package as a whole, I decided to install all the bolt-on components in order to round out the setup."
It's easy to see why the Stage 2 ECU software caught Keyes' attention. Unitronic says that, while maintaining an OEM-like power curve, the software can deliver gains of 80 hp and 118 lb-ft of torque when paired with Unitronic's 3-inch downpipe, which puts a MK6 GTI at 280 hp and 325 lb-ft without any other modifications. "The ECU stage 2 tune was a huge change from stock," Keyes says. "An increase of 80 hp over 100 lb-ft of torque was something I felt immediately." Keyes used Unitronic's UniConnect+ handheld tuning interface to install the tune, which gives owners the ability to apply the ECU software from home and make adjustments to the tune as needed. On top of that, the system gives users the ability to perform diagnostics or set the software back to stock.
The company's turbo-back exhaust system is on hand here as well, which includes the 3-inch downpipe required for Stage 2 ECU tuning. The 3-inch stainless steel system features a high-flow catalytic converter and is a direct bolt-on system utilizing all the OEM mounting points. Though the performance increase it offers is negligible by the company's own admission, it does give the GTI a decidedly more imposing bark. "I like the exhaust because it is pretty quiet when cruising," Keyes says. "But when you get on it, it has a nice, deep tone that isn't annoying."
The company's cold-air intake system is a similar story, offering direct bolt-on fitment and high-quality 6062 and 5051 aluminum construction, along with a 33 percent increase in airflow over stock. But like the exhaust, its performance benefits are largely of the sonic nature, as the open element design makes the turbocharger's various whooshes and hisses more audible but offers little in the way of output gains.
Horsepower isn't the final word in performance, though. Upgrades like the company's intercooler kit—which boasts 64 percent more volume than stock and is far more resistant to heat soak while significantly reducing charge air temperature—should help this tuned GTI deliver consistent performance on the track during repeated lapping sessions. Similarly, Unitronic's Diverter Valve Relocation Kit moves the diverter valve away from the heat generated by the exhaust manifold to improve durability and responsiveness.
Unitronic's Stage 2 DSG software is the final piece of the puzzle, which increases the rev limiter to 7,000 rpm, sets the launch control system's parameters, and applies various tweaks to the DSG's software in order to improve responsiveness as well as driveability. "The Stage 2 DSG tune also got rid of the kickdown on the throttle," Keyes points out. "And it also gave me multiple launch control rpm options, so I can fine-tune launch control for different road surface conditions."
All of this sounded promising, but putting the car through its paces on some demanding stretches of road would allow us to get a real sense of these modifications' worth, so we headed to the San Gabriel Mountains northeast of Los Angeles to do just that.
Behind the Wheel
"Doing straight line pulls never gets old," Keyes quips as I dip generously into the throttle coming out of a low-speed bend. Indeed, a 40 percent increase in horsepower over stock is very noticeable, and this GTI now accelerates with haste similar to a MK7 Golf R—once the front tires find traction.
What's perhaps more impressive is the relative absence of torque steer, though I theorize that this might be attributed to the fact that the additional power is all coming from the turbocharger, and therefore off-the-line output is not dramatically different from stock. But the sudden surge of power from the boost is much more noticeable as a result, yet it's worth noting that the amount of revs required to get the turbocharger's attention remains similar to that of a stock MK6 GTI.
It sounds the business as well. The exhaust system is well tuned, offering a rorty yowl when pulling through the gears and settling down to a drone-free thrum while cruising. The intake plays a legitimate role in the aural theatrics as well, with the forced induction system adding some emotive, yet subtle, sounds to the mix when transitioning on and off throttle.
The software tweaks to the gearbox translate well, too, but in a more understated way. We've never considered Volkswagen's DSG transmission to be a slouch when it comes to shift speeds, but the Unitronic tune somehow feels more urgent and responsive without introducing any additional harshness. Having a few hundred extra revs to work with at the top end is nice as well, though the engine is done building more horsepower by about 6,000 rpm in both the stock and Stage 2 tunes, while peak torque with the Unitronic tune comes in around 3,000 rpm and levels off until about 4,500 revs, where it begins to gradually drop off.
From our time spent with Alex's GTI, it's hard to see much of a downside to Unitronic's Stage 2 package aside from the fact that it has the potential to elevate the motor's capability to a point where it's no longer balanced with the stock hardware found elsewhere on the car, like the factory brake setup on Keyes' GTI. "Those are next," he assures us. And therein lies the rub—once you start modifying a car, it can be hard to stop, because each time you improve one aspect of the vehicle's performance, it can exaggerate the weaknesses of others.
But after our seat time in Keyes' GTI, it's clear that Unitronic's powertrain tweaks deliver on the promise of OEM-like driveability while providing a significant boost in performance. Like most tuning outfits, Unitronic also offers each component separately, which allows owners to do their upgrades incrementally or simply pick and choose which components they want to add to their setup, and they're backed by both a 15-day satisfaction guarantee as well as limited lifetime warranty for the original purchaser.
At about $4,200 all-in before any applicable discounts (and without taking into consideration any installation costs) the package as a whole is a significant investment. But considering that the lion's share of actual performance gains are had from the Stage 2 ECU software and downpipe, the cost of entry to step up to this level of straight-line performance is significantly less than that, albeit without the benefits inherent to the rest of the package.