As for the camshafts: "Normally you can put a wilder cam in a larger capacity motor," Nowack explains. "But today's clients do most of their driving between 2500 and 5500 rpm, so I went for a cam profile with a shorter duration, lower lift and less overlap. The result is more torque, better fuel economy and full functioning of the VANOS system."

The fuel injectors are stock and the fuel rails pressurized to 7.0 bar by the two stock pumps. It turned out that the stock injectors and fuel system had enough headroom and work just fine. On the induction side, high efficiency air cleaners in the modified airbox feed ram air into throttle bodies bored from 50 to 52mm. The dirty side of the engine wears a bespoke exhaust system with Nowack headers, 200-cell cats, free-flow rear silencers and 68mm diameter pipework.

Despite the larger capacity and greater output, aside from some special coolant for the radiator, testing revealed that no extra oil cooler was needed. A twin-plate clutch with semi-race organic lining takes power to the SMG gearbox, whose control protocols were re-mapped to work with the new power and torque curves.

When a car this size knocks on the door of 200 mph, it takes a lot of stopping power. Nowack use the largest Brembo brakes that will fit the front axle: massive 405mm cross-drilled and vented rotors with eight-pot calipers and high-performance pads. As most of the braking is done by the fronts, the factory rear brakes were adequate. All the brake lines were replaced with stainless steel braided hoses, and DOT 5 fluid was pumped into the system.

To harness the extra power, H&R supplied new race-style, height-adjustable coilovers. Since the factory damping is electronically controlled, these units have an added refinement in the form of an auxiliary electronics pack that interfaces with the ECU to make it think all is normal and prevent it from throwing up a fault code.

The M5 already has a front strut brace, so when you open the hood, it all looks normal. However, Nowack uses one with slightly larger diameter tubing, while under the car the stock anti-roll bars have been replaced by three-position adjustable bars, 2mm larger in diameter.

Nowack's distinctive alloy wheels are 9x20 and 10x20 with 255/30 and 285/25 tires front to rear. The Avon ZZ3s make for an unusual choice of rubber, but after testing a variety of competing tires, Nowack concluded that these strike the best balance between performance and comfort with this suspension.

Changes in the cabin are minimal, the most salient feature being the lightweight Recaro seats. The recalibrated speedo now reads out to 360km/h and the rev counter electronics were modified to take the higher rev limit into account.

While they can be fun when you're in the right mood, high-revving engines that lack low-end torque can end up being tiresome for everyday use. The Nowack 5.7 cures that problem by giving the M5 both copious low-end grunt as well as its ballistic, racecar-grade top end.

I was so impressed that I want more-but not actually more power. You see, I'm having this recurring dream about using the 5.7 in a mid-engine supercar weighing less than 3,000 pounds.

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