The kit adds an extra 23 horsepower to the hatchback's 2.0-liter turbocharged four-cylinder engine, taking it from 252 hp to 275 hp. Torque is pegged at 296 pound-feet with the addition of the kit.
The Focus ST retains the factory warranty when installation is performed by an authorized Ford Performance technician. The base Focus ST has a three-year/36,000-mile warranty.
Ford said the setup "optimizes performance without sacrificing reliability."
The package includes a new air-induction kit, a high-flow intercooler, mounting hardware and a handheld programmer tool for reflashing the car's engine computer.
Ford said the Mountune system keeps the Focus ST street-legal in all 50 states.
Edmunds says: Installation prices will vary from dealer to dealer, but this package gives the Focus ST a boost at an affordable price.