the GT2 993s all had bolt-on fender flare extensions at the wheel arches so they could get bigger rubber on the car.

Same deal with 993 RSRs. Stock 993RSR was same as any garden variety 993 you would see in any parking lot. Optional were bigger tires & wheels which dictated GT2 turbo dba wheel arch extensions.

Back to the orginal question. If I were making a GT2 out of a 2 wheel drive 993. I would skip[ the arches and cutting up the bodywork. Just stuff a 993TT engine with GT2 powerkit and catbypass pipes into a 993 RS Clubsport. At 2750lbs with a Airconditioning and CD radip with powerwindows.........and500ftlb you will have one fast blazing ride that no street based Porsche can keep up with unless they are really carrying a bigstick.

 

More on the Cup 3.8 RSR: Even though it was called "cup", it was never used in cup races. It was made expressly for the Japanese GT championships, as well as for the imsa GT3 class.