what compression is needed for 91 octane

I live in Cali, feel the same way.(91 Cali pee water sucks...) However, that is too vague a combination, to recommend a clear answer. How about more info, on the combination? ( makes for a more concise response..) Let's, start there.....

agree w/ rrr and kimmer,I run alum. heads 10.3 c.r. on 91 oct, no problem. timing is everything!