my bike don't like u2 it pings under full load (i really need to cc this girl and find out where im at, i was getting 220lbs with my snap on gage and i just had the head cut again). and i don't think VP offers u2 any more. i think it was replace by u4.2. i might give u4.2 a chance it looks to have a little more motor octane. i have had good luck with c12 but like the extra power you get with oxygenated fuel.