You said 97 octane premium fuel i did not, its rated that 93 octane is preferable for its high compression, altho 91 will suffice, and there is 93 octane pumps, There is BP here which i know yu guys have there, and it goes from 88 to 91 to 93. And no here they are NOT stamped K20A2 or A3, a person in america that has had a real Asian market(JDM) engine knoes that, thats how yu spot a phonny JDM engine, in the asian markets It goes H22A and america there was an A1 and A4/ C32A/C32B there is No number after the alphonic place of the last letter, thats only for USDM market models. Sure they are Tuned diffrant to to give more or less HP thats wut thats about, as A2/A3 or even A1 engines in america just use diffrant parts to give the decrease or increase in HP.Just ask anyone that is a JDM pro about JDM and USDM engine stampings.