The car benefits from a multipoint roll cage, designed to be HANS® compatible as required from January 2007. The design complies with Appendix J of the FIA International Regulations. It includes 3 x 'X'brace in the rear of the car including above the passengers heads and 'twin tube' door bars with no cross-over. The cage can be bolted or welded to the chassis and does not require the dashboard to be modified, further aiding the installation process.
 

The basic engine remains standard with the only additions being a revised 'foam' air filter. The engine ECU has been modified to revise the fuel and air ratio and optimise the ignition. Modifications have been made to the 'pedal map' for the electronic 'fly-by-wire' throttle which improves throttle response and engine torque in the lower gears.

The standard ST front and rear disc brakes are retained. The pipes in the braking system are replaced by braided steel hoses and an adjustable pressure-reducing valve is fitted to the system while still retaining the dual circuit diagonal braking required to comply with Gp.N regulations. The brake pad compounds have been optimised for rallying.

A substantial 6mm aluminium sumpguard to protect the engine and transmission components, manufactured to an Ford Rallye Sport Turkey design, has been added. The std. fuel tank has a Kevlar composite moulded guard to protect from stone damage. The fuel filler neck also has a Kevlar composite moulded guard to protect this area. There is also optional underbody protection available to protect the floor pan and the side sills from stone damage.

The car has a 5-speed 'dog' engagement gearkit fitted to a standard ST casing. The gearbox design and ratios have been developed in conjunction with SADEV. The transmission is supplied as an exchange item ready to fit into the car, with the customer to return their std. ST gearbox in a serviceable condition. The STGp.N features uprated driveshafts as standard.

Taking advantage of the std. vehicle features, M-Sport has been able to homologate the ST to use 15" wheels for gravel and 17" wheels for asphalt to take advantage of the increased range of tyres for these popular sizes. The wheels for the Gp.N version of the car have been manufactured by DJ Wheels.

The majority of the trim as authorised under Gp.N has been removed from the car to reduce the weight and allow the fitment of the safety features required in a rally car designed to compete in any region. The seats have been replaced with Recaro competition versions made from composite materials. To these have been added Sabelt 6pt harnesses, a Sabelt suede steering wheel plus an integrated fire extinguisher system with electronic control

A 'piggy back' wiring loom has been developed to supplement the std. car wiring loom, incorporating the additional electrical requirements of the rally version. This includes an electronic circuit breaker to cut power to the electrical circuits in the event of an accident. It also includes the wiring for additional electrical requirements like map light, additional spotlights, radio, tripmeter etc.

Using the uprated suspension of the std. ST as a basis, which includes revised front suspension knuckles for additional negative camber and a strengthened twist beam rear axle, M-Sport engineers have added Reiger dampers which are adjustable for rebound and revised spring rates to improve the ride over rough surfaces found on stages. In addition the steering rack on the standard ST Gp.N has a quicker ratio than the standard Fiesta to give improved turn-in.