Ever wonder what it would be like to greet the coming summer season with a high-performance convertible that’s been tuned to be faster and more powerful? Well, those questions could be answered if you own a BMW M4 Convertible and you’re in the market for an aftermarket tuning program. German tuner G-Power->ke1323 has all your needs covered with a new tuning kit designed specifically for the M4 Convertible.->ke4183

The kit follows the typical style of G-Power. There aren’t that many exterior and interior enhancements, but the lack of mods in these two departments are made up for by an engine modification that puts a significant amount of extra power on the M4’s 3.0-liter turbocharged inline-six cylinder engine. It may sound trivial for some, but for those who appreciate 600 horsepower on the M4, this performance kit should be right up their wheelhouse.

To be fair, G-Power has built programs for the M4 before. But this is the first time that the tuner has taken a stab at the M4 Convertible. The good thing is that G-Power is renowned for being one of the best tuners of BMW->ke178 vehicles in the world so if you’re going to have your M4s worked on by an aftermarket company, the German tuner is one of the safest bets to get the job done. If for nothing else, you can always count on a company that has 30 years of experience doing these kinds of modifications.

Continue after the jump to read more about the BMW M4 Convertible by G-Power.

Exterior

As expected, there are very little modifications to the M4 Convertible’s exterior. There are no aerodynamic kits and there are no fancy body wraps, although if you want to be technical about it, there are a few blacked-out parts, including the front grille and the taillights. That might be disappointing for some people, but if it’s any consolation, the German tuner is offering a new set of 21-inch Hurricane RR forged alloy wheels as part of the whole program. The wheels measure 21 x 9.0 and 21 x 10.5 in size and are shod in 245/30R21 and 295/25R21 high-performance tires, respectively.

Interior

The same holds true in the interior of the M4 Convertible. While it would’ve been nice to get some upgrades on the cabin, it’s hard to fault G-Power for brushing off this section in favor of concentrating its effort on giving the car the performance upgrade it deserves. Besides, it’s not like the M4 Convertible has a mediocre interior. On the contrary, BMW already did most of the legwork by giving the cabin plenty of neat details, including the M specific stitching and badges that help distinguish the M4’s interior from standard 4 Series convertibles. Sports seats and fine leather are also included in the interior styling so this section is already well taken cared.

Drivetrain

Suffice to say, G-Power carried out significant modifications on the M4 Convertible’s 3.0-liter turbocharged inline-six engine. At the heart of this modification is the tuner’s Bi-Tronik 2 V1-ECU remap that by itself already increases the output to 520 horsepower and 516 pound-feet of torque. That already represents an increase of 95 ponies and 110 pound-feet of torque.

But G-Power has shown time and again that it’s never content with “slight” upgrades. So it went out and concocted an extensive combination of hardware and software upgrades, beginning with the replacement of the standard compressor wheel with a larger CNC-milled unit. G-Power’s engineers also worked on the exhaust turbine wheel, which helps drop exhaust gas temperature and improves boost pressure. Even the turbocharger’s housing unit was machined to accommodate the new compressor and exhaust turbine wheels. Optimization of the internal gas flow was also carried out, completing the comprehensive upgrades on the whole engine setup.

All these upgrades contributed in increasing the output of the M4 Convertible’s turbocharged inline-six engine to 600 horsepower at 6,500 rpm and 546 pound-feet of torque between 4,000 and 5,500 rpm. The results are eye-popping and no more was that evident than in the car’s improved performance numbers. Yep, this engine modification was enough to allow the sports car to sprint from 0 to 62 mph in just 3.7 seconds, half-a-second quicker than the standard model. Likewise, top speed has been increased to 199 mph, much faster than the M4 Convertible’s electronically limited top speed of 155 mph.

So the extra power and speed are already there. But it's still not enough to really appreciate the full G-Power experience. The tuner addressed that by installing a bespoke ultra-lightweight titanium exhaust system that delivers the kind of exhaust note you can only get from a tuner like G-Power.

Suspension

It’s hard to make such an exhaustive tuning kit without addressing the car’s suspension. Fortunately, G-Power understands the need for corresponding upgrades to accommodate the increased output. So it included its very own GM4 RS coilover suspension to address that need.

Pricing

The total cost of the kit is €24,372.86, excluding taxes. That amounts to $27,572 based on current exchange rates. It might be steep for some people, but with the kind of upgrades that come with the kit, others shouldn’t have a problem with the cost that comes with it.

Competition

BMW M4 by CarbonFiber Dynamics

Since there aren’t that many tuning programs for the BMW M4 Convertible, I’ll take a different route and put the focus on competing kits for the convertible’s coupe counterpart. One tuner that just presented its own program for the M4 was CarbonFiber Dynamics. This program comes with an extensive naked carbon fiber body kit made up of a front lip spoiler, side skirts, a ventilated hood, an adjustable rear wing, a rear diffuser, and a trunk-mounted spoiler. It also has a new set of 20-inch BBS wheels shod in Toyo Proxes T1 tires.

Under its hood, the M4’s inline-six engine received a nice upgrade of its own. Modifications on the turbochargers and the addition of a new air intake and a high-flow air filter are the highlights of this kit. In addition, a methanol injection kit and a tuning module from Burger Motorsport JB4 that comes with fine adjustment and CANBUS command with eight different ECU maps are also part of the program.

Add all these up and you get an M4 with an output of 600 horsepower and 610 pound-feet of torque, right in the neighborhood of G-Power’s own tuning program. CarbonFiber Dynamics didn’t specify the performance numbers, but considering its proximity to G-Power’s own kit, a 0-to-60-mph sprint should be good for around 3.5 seconds to go with a top speed of close to 200 mph.

Read our full review here.

BMW M4 by B&B Automobiltechnik

Ever since the calendar flipped to 2016, we’ve already seen a handful tuners present aftermarket programs for the M4. One of the first to do it was B&B Automobiltechnik, which presented a similar kit to what G-Power has on offer for the M4 Convertible. Suffice to say, exterior changes were limited to just a new set of wheels while the interior was left to its standard configuration.

B&B focused its attention on the M4’s turbocharged six-cylinder engine. In fact, the tuner not only created one tuning package, it created three, each with varying levels of power increase. All three stages came with modifications to the turbochargers to go with a higher-flow intake tract, larger exhaust downpipes, more efficient charge air cooler, and an ECU remap with revised fuel, spark and boost parameters.

With these mods in place, B&B was able to extract 490 ponies with the Stage 1 kit, 540 horsepower with the Stage 2 version, and 580 horsepower and 553 pound-feet of torque with the Stage 2 kit. The most powerful of these programs gave the M4 a 0-to-62-mph of just 3.5 seconds to go with a 205-mph top speed.

Read our full review here.

Conclusion

I don’t need to be convinced about anything that G-Power does, especially when it comes to tuning programs for BMW models. This kit is everything you’d want for your M4 Convertible, other than the absence of any exterior and interior modifications. I get it if some people don’t appreciate it as much others do, but for me, that 600 horsepower output is all I want to give the M4 Convertible that bite it needs when it hits the summer road.