After two years with Fred Gibsons "works" Nissan team in 1986-1987, young but very experienced Glenn in his early 20's and his father well respected race engineer/driver and Bathurst winner Barry, set up their own workshop in Dandenong (Victoria) and in 1988 imported two factory prepared body shells from Ford Competitions Department in England, one of which is chassis no. RS155 being part of a homologation build of 500 cars required to be built to be eligible for Group 'A' saloon car racing worldwide.

The car was then constructed in their workshop using Harrop suspension components including hubs, drive shafts, axles, uprights etc. where permitted within the rules. Barry built the two litre Pinto based wet sump 4 cylinder 16 valve twin cam engines employing a Garrett modified M24 turbocharger with a large intercooler producing up to 2.4 bar of boost (over 30 lbs.) and around 580 horsepower on around 6.2 to 1 compression ratio with nearly 500 ft. lbs. of torque depending on boost settings.

A competition 5 speed Getrag gearbox was initially used but later a 6 speed locally made Hollinger stronger "crash" box fitted to overcome "turbo lag" between gears and offer more ratios at the circuits.

Weighing in at a regulation minimum of 1200 kgs including ballast, the Sierra was fitted with 17 x 8 inch BBS wheels initially and later in their development used 17 x 9 inch 5 spoked specially constructed Dymag magnesium alloy wheels (for Sierra's), which allowed larger tyres to be fitted. With their enormous "sudden" power around 6500 RPM, race Sierra's needed as much rubber on the road as possible. Also installed is a solid under-floor mounted aluminium case lightweight differential that is cross braced by the simple but "busy" internal roll cage/body stiffness chassis, which ran with a spool centre (locked), separate oil cooler, auxiliary pump and used multiple standard Ford 9 inch ring and pinion sets for circuit ratio changes.

Braking is handled by large ventilated 330 mm AP disc rotors front and 300 mm rotors on the rear both with 4 spot AP calipers with a cockpit graduated bias adjustment control and a digital readout.

A 120 litre bladder fuel tank is fitted with dry-brake attachments for fast filling and safety in long distance races. Avgas fuel only is used.

The body is all steel with fibreglass attachments such as front splitter, rear bumper and rear wing but the cars internal include a basic but modified dash, door padding, a special lightweight fibreglass race seat and 5 point race seat belt harness and of course there are multiple gauges advising turbo boost, revs, diff and engine oil temperatures, volt and amps, water temperature and so on.

Engine management was initially handled by a Zytec EMS computer but later replaced by a much more user friendly Autronic system which allows the cars engineer to easily download to a laptop using a co-ax cable, analyze the engines behaviour, fine tune at any time when the car is stationary making adjustments where necessary.

When raced in Australia between 1987 and 1992, all the Group 'A' RS500 Sierra's were rev-limited to 7500 RPM with an additional "black box" installed on all cars by CAMS (Confederation of Australian Motor Sport - the controlling body), to avoid excessive revs and subsequent engine "blow ups" but with the boost turned up to 2.5 or 2.6 bar done in some cases by others to achieve over 600 bhp but without caution the Sierra's were known for their engine unreliability. Many Sierra's were timed at over 300 kph (200 mph) on Bathurst's notorious Conrod straight especially during qualifying!