Manthey takes Porsche's 911 GT3 RS to a rarefied state of single-mindedness - and we take it to Silverstone When the current 911 GT3 RS landed, it appeared Porsche - Zuffenhausen, the mothership - had finally pinned motorsport satellite Manthey into a development dead end. This mattered because tiny Manthey's ability to turn a showroom-spec GT-division 911... [2466 chars]