If you look closely at the "R" front splitter and compare it to the non-"R" splitter, you will see it is larger and more aggressive to create more downforce. It was designed to work with the "R's" rear wing, not the rear spoiler that is on the normal GT350. I am told that if you are going to put an "R" splitter on the front, you need to put the "R" wing on the back to maintain aero balance. And putting the "R" wing on the back is a real PITA...