The GT3 RS is the naturally aspirated 911 road car, with 513bhp from its four litres. The suspension is far more focused than the regular GT3, the aero kit generates much more downforce, and there's yet more power and torque from the 4.0-litre flat-six, which itself is closely related to the racing engine used in the 911 GT3 Cup car.The GT3 RS weighs around 1430kg, but the optional Weissach pack can cut weight by as much as a further 28kg with innovative composite anti-roll bars and suspension components, a CFRP roof to replace the magnesium panels ordinarily fitted to the RS, a similarly carbon weave finish for the bonnet also.