i used 95 octane, just put the tmap sensor 3.5, pcv upgraded valve. and purchase M license option from mhd. already have this mods: Current Modifications: i have a 2010 bmw z4 35is and with 40k miles a the mods are: vrsf down pipes,stock inlets, vrsf 7.5 comp intercooler, chargepipe with tial blow off, dual cone intake burger, already installed mhd stage 2+ with monitor license. i change the injector index 8 for index 12, already purchase ngk spark plug with 1 step colder. ZR5TPP33S version 7 by wedge performance