Theon Design is marking its 10th anniversary with another custom Porsche 911 build, this time starting with a 964-generation donor car. Built at Theon's Oxfordshire headquarters, this latest commission took 18 months and combines a 419-hp, 4.0-liter naturally aspirated flat-six with plentiful carbon-fiber bodywork, a modern suspension, and a cabin finished in Beechnut leather. The end result weighs just 2,535 pounds, according to Theon. The car wears a coat of Oak Green Neo Metallic paint as a nod to Porsche's classic Oak Green, and pairs that with champagne-colored Porsche lettering and 17-inch wheels. Underneath, Porsche 993 RS brakes provide the stopping power. The engine is a naturally aspirated flat-six produces 419 hp and 322 lb-ft of torque, with selectable engine maps that allow the owner to change its character depending on the situation; for example, a "town mode" makes the car less aggressive for everyday driving. Power gets shuttled to the rear wheels through a five-speed G50 manual transmission. Theon Design Theon says its approach is less about turning an old 911 into a modern supercar than refining what made the original special. The company strips each donor car to its bare shell before rebuilding it, updating the mechanical but maintaining the spirit and proportions of the 964. The carbon-fiber body panels alone save roughly 660 pounds compared with the original car. The chassis has been tuned specifically for British roads, says Theon, using TracTive semi-active dampers, custom spring rates, and revised steering. The 17-inch wheels are fitted with Michelin Pilot Sport tires with relatively tall sidewalls, giving the car some extra compliance on rough pavement. Theon says the goal is to combine sharp turn-in and body control with enough ride quality for longer trips. There are less obvious upgrades, too. A new electric heating and air-conditioning system replaces the original, while a lightweight military-spec wiring harness saves about 55 pounds. Even the window switches have been redesigned and machined from aluminum. Theon Design The latest car arrives as Theon continues development of its more extreme Theon R, which is targeting more than 500 hp and a curb weight below 2,205 pounds (1,000 kilograms). The first customer R is currently under construction. Theon has also launched an online configurator for its Coupe, Targa, and R models and established a US presence through Humble House, giving American customers local concierge support. Coupes start at $575,000 (£435,000) before the donor car, shipping, and taxes.