[kach22i]

https://www.fordmuscle.com/features/car-features/blue-oval-icons-the-mclaren-m-81-mustang-is-an-uncommon-fox/

At more than three times of the price of a GT, it was clear from the outset that the M-81 was never destined for mass production. But even the goal of building 250 examples in total proved to be too much. Just ten would be produced, along with the original prototype. Image: Bring a Trailer..............................

But perhaps the most significant element of the M-81 package lurked under the hood. Using factory 2.3-liter blocks, McLaren blueprinted, polished, and de-burred the engines to bolster durability. While the 9.0:1 engine were mechanically similar to the factory turbo four-cylinder mills, McLaren allowed for the powerplant to handle more boost from the Garret T-3 turbocharger. Although 175 horsepower might not sound like much today, it was an increase in output of more than 30 percent versus the standard turbo four-cylinder’s 132 horsepower. A pair of car were also reportedly outfitted with adjustable boost controllers, while a range of 5-11 psi allowed the engine’s output to potentially be ratcheted up to 190 horsepower and beyond.