On an 11:1 compression, can 91 octane be used? I'm going to the dyno to tune the new motor so I image the technician will be able to tune it with 91 octane gas....Or I MUST use 94 (we got that here in Montreal). With the gas prices these days, I 'd like to use 91.

 

you should be fine but if you have access to 94 octane I'd take advantage of it

 

91 is just fine on that. I'm at 11.5 and no trouble tuning on it at all.