i've never tried the q3, but the q2 is a very capable tire and i've heard nothing but great things about the q3 and that its at least a minor improvement over the q2. that all said, i never pass up cheap tires. i generally save up a few hundred for every winter so i can snap up cheap race tires where i can find them. i'd say if you're not running mid pack to upper advanced lap times, you probably won't notice the difference between any of the street tires meant for a balance of track day/street riding (specifically, Q2/Q3, pilot power, power 2ct, pures, etc). buuuuuuut, track riding is a LOT about your comfort level and trusting your tires, so you should go with what makes you feel most confident.