Just wondering how much of a difference it would make. my car is from hawaii and we run 92 octane with 10% ethonal. im not really sure about how the change to 91 octane(not sure about the additives here in CA) but im just wondering on the affects on the tune.

 

It really depends how aggressive your tune is now. If it's close to edge, you can bet your Greddy twins that you'll see some issues when you change over to the California sorry excuse for premium gasoline ****. You were getting a healthy dose of alcohol in your previous mix which was actually helping you. Ethanol is great for performance. Be cautious and expect that you may see some issues, especially at high loads. The change isn't huge but give that you had alcy in your gas before and now you're going to Cali infamous gas, be ready.