Some insight would be great here.

A local Superchips Dealer told me that I may experience some knocking if I try to run my 04 FX4 in the performance mode (91-93 oct). What do you guys think? I spoke to Superchips and they said no way. I am at 5500' ASL. Any info would be appreciated as I am on the last quarter tank for the 87 octane and I really want to try the 91-93 octane. Thanks JP

 

I have had my truck set on the high performance mode now for about a month. The only time I had any knocking was when I first started it up after the install. Since then no knocks and the truck runs get. The only thing I do not like is when it is time to fill up with the premium fuel. But with the differance in the way the truck runs between the 87 and 91-93 settings I am willing to pay the extra for now.

 

SUNION - What elevation are you at? That seemed to be the concern.

 

Moved to Computer Tuning forum

 

Try it. If you get pinging, revert to the 87 octane tune until you can put some more premium in.