McLaren Automotive is known for creating some of the greatest driving machines of the last two decades. Initially aiming for Ferrari with the MP4-12C, it has since introduced a range of supercars, such as the 765LT, which forms part of the brand's Super Series. But if you're craving more, the carmaker also offers an Ultimate Series, with vehicles such as the retro-inspired Elva.

The now-discontinued P1 was also a part of the Ultimate Series. With a 903-horsepower, electrically-assisted V8, improving the performance would be a tall order. But UK-based Lanzante Limited has done just that, increasing the displacement of the 3.8-liter V8 for a special customer. Now measuring 4.0 liters in size, the already muscular V8 now produces over 1,000 horsepower.

As per Evo, the lucky buyer requested upgrades to the engine. To achieve this, Lanzante knocked on Cosworth's door for help. Aside from the higher power output, the torque curve is reportedly more linear than it is on the original P1, providing a better response. Capable of hitting 186 mph in 16.5 seconds, the McLaren P1 was already a very quick hypercar. We can't imagine how quick the uprated 4.0-liter must be.

Lanzante hasn't just stopped at engine enhancements. The British firm also offers P1 owners a unique High Downforce Kit bodywork which is supposed to harken back to the HDK available to owners of the iconic McLaren F1. The end result is beautiful, lending the P1 plenty of presence and aggression. The green-painted example seen below was built to the client's exacting requirements and the rich color works really well with the stunning saddle tan-colored Alcantara seats.

To support the new aesthetic enhancements, Lanzante fitted uprated suspension components to handle the extra aerodynamic load afforded by the HDK bodywork. Paying tribute to the F1's various gold-plated engine parts, the company has also used gold heat shielding in the P1's engine bay.

Unique styling touches include satin gold brake calipers, HDK badging, and lightweight carbon fiber wheels, while the cabin boasts carbon-fiber trim and new pedals.

No mention of the price is made but, last year, the first-ever example of the P1 went up for auction with an estimated price of more than $1 million. We're guessing the extensive work needed will easily be a couple of hundred thousand dollars, judging by the level of craftsmanship. But if you can already afford a P1, the enhancements should be pocket change.