Sow&Steady- When I refer to the split I was talking about the difference in shore. Instead of a 35Shore front with a 40 shore rear I would run a 38shore front with a 40 shore rear. This also makes the car easier to drive. I try to run a 1-1.5 mm split front to rear. In qualifying I write down my tire wear at different times throughout the day and measure it. I keep this in my notes for later to use in the race.... I have never run the 18t conversion. In my car the only options I have on the car were the top deck mount in Aluminum and the skyline rear link mount. This is before the Serpent SDD came out...
I hope that helps!
Rafael