What kind of gasoline octane is recommended for JDM engines once they are installed to USDM cars?

I purchased a EG6 front clip and installed everything onto my 93 hatch. My friend was telling me that I needed to keep the Octane at least 91 Octane..... Is that true? What # of Octane do ppl use over in Japan? does anybody know?

 

you need 91+ to keep your b16 performing the way it should. you can get away with less but performance and life span diminish.

 

guess my friend was correct... what # Octane do they use over in Japan? My friend had told me that they use a very high Octane due to emission or something? ??????

thanks for the info regarding 91 octane....