i just put on a pirelli tire on the back and still have the dunlop 207 on the front. the guys at the shop said that the pirelli is a bit softer than the dunlop so the front will push a bit in the twisties. i dont really think it is that big of a deal though considering racers use different compounds all of the time. also in a wet/dry race sometimes they will put a rain front with a dot rear and that has to be way different. i know they are pros and everything but it just doesnt seem like a big deal to me. i went on a pretty long ride this weekend and didnt really notice a difference beside that it handled better with the new rear.