91 isn't going to hurt you. Cars are tuned to be able to run the gas available. Worst case it backs off timing with lower octane. I ran 91 here in CA for the first 40k miles until I converted to E85. I actually ran it with ETS intake and UR Cat back with zero problems.

 

For future reference, the 2014 manual stated that it recommends 93 octane. 91 is fine but you'll get less power

 

Less power but who knows if it's noticeable.

 

That does make me wonder if anybody has taken the time to dyno a stock X on both octanes just to see.

 

My guess is that has done it and put that line in the manual. I'll be a pretty cool experiment to run thought.

 

91 Octane on 21k miles and still running good

 

As a californian...**** 91, but its all I have

 

Any good 93 pumps in the bay area preferably south bay?

 

Ive been running 91 and had no problems at all
I did find a station (seriously like 1 out of 1,948,374 ) in town that has 93 and i do notice a slightly better throttle response on 93. It's not a massive difference but it does feel smoother

 

i use 93 cause thats whats here in florida

 

Get an accessport and flash the appropriate 91 map for a quick way to get a good tune. They even have california specific 91 maps.

 

Does the Accessport void the warranty?

 

Yes.

 

If your OM says 93 octane then 91 will be fine. There's usually a given tune which will also allow a "safety net" for the everyday driver. You will probably experience a slight performance drop by using less octane and you should not have to tune it for 94 octane.

I had the same question before and called a dozen Mitsubishi Dealers and they also said that it won't affect your warranty by using 91 octane. So... you're safe.