You should run 93 before you tune for 93, the main power adder with all tuners is advancing the timing, in theory your advancing the timing by around 6 degrees from 87 to 93 octane, if you don't run 93 and tune for it your gonna get detonation(spark knock, valve rattle whatever you want to call it) you could damage your engine. Another good thing to remember is most fuel today is gonna have ethanol so that can lower the octane rating alittle in itself.