In 2024 we came to Silverstone with a regular 911 GT3 RS to explore how the car’s new cockpit-adjustable damping and differential controls affected the driving experience. That day wasn’t just about subjective driving impressions. We also recorded a lap time, and this has come in handy, because now we’re back at Silverstone – and in very similar conditions – with another GT3 RS, and this one is equipped with the £99,999 Manthey package. Manthey’s kit doesn’t add any power to the standard car’s 518bhp output but it does bring a host of aerodynamic and suspension modifications. How much faster does all this really make the amateur trackday driver? Time for deputy road test editor Richard Lane to set a lap time and find out.…