The Porsche 911 GT3 Cup Challenge GB switches focus to the Rockingham Motor Speedway in Northamptonshire this weekend (10/11 August) for the fourth of six double-header meetings for the fabulous 420bhp racing Porsches as used in the Carrera Cup GB up to 2009. To date it has been a perfect season for Justin Sherwood (Team Parker Racing) who has been unbeaten across the first six races to take a 16-point championship lead. Sherwood has not put a wheel wrong so far and will now head to Rockingham aiming to extend that mighty sequence to eight races. With drivers counting the scores from their best five of the six race weekends, Sherwood has a handy cushion but he would love to finish the season with a perfect 12 victories.The man most likely to upset Sherwoods plans is his team mate Steven Liquorish, one of the most experienced Porsche racers in the championship. The Oxford racer has finished second to Sherwood in all six races to date and would love nothing more than to see the chequered flag before his team mate. Liquorish has taken three pole positions to date, so his pace is clearly very strong.Emmerdale actor Kelvin Fletcher has made a big jump up the racing ladder this season to join the GT3 Cup Challenge and showed excellent pace last time out at Croft when he scored a brace of podium finishes to record his best weekend of the season to date. Fletcher races with Redline Racing, one of the leading teams in the Porsche Carrera Cup GB.Racing newcomer Peter Kyle-Henney has been the revelation of the opening three race weekends, taking three podiums for Parr Motorsport. Having previously taken part in track days and speed events, Kyle-Henney has raced superbly despite his lack of prior racing experience, although he will head to Rockingham seeking to make up for a mixed weekend at Croft.Back for a second season in the GT3 Cup Challenge is Yorkshireman Guy Riall (Almara Racing), and he showed ever-improving pace last time out at his home track of Croft.Qualifying at Rockingham starts at 13.00 on Saturday, with the 25-minute races scheduled for 16.55 on Saturday and 14.20 on Sunday. The action can be followed on the new Porsche Cars GB Trackside motorsport web platform at www.porscheracinggb.porsche.com