Upgrade injectors & fuel pump and Go E-85. My .02 cents.

 

All Evos are made for gas with an octane rating of 91 or higher. You're fine with either choice. The 94 is slightly better than the 91. Go with it if it doesn't hurt your wallet. The 91 is NOT going to hurt your Evo.

 

Most of the propane/natural gas dealers have a top tier 93 octane or better ethanol free gasoline available. Some have gas pumps, others will sell you your own fuel tank and come fill it for you. So for all you guys that live in colder climates in the winter it might be worth looking into.

 

I found one chevron in Gardena on Western Ave and Artesia that sells 92.

 

I wish Shell sold 93 Octane here, that'd be awesome. I've been using Husky 94 though, and the car is running great.