i just bought a superchip flashpaq for my 2008 ram 1500 5.7hemi with a cold air intake and dual exaust. On the tuner there is an 87 octane mode and a performance 90something octane mode. My question is if I'm just running regular unleaded fuel, will that performance mode do any harm to my truck? The flaspaq manual doesn't have much to say about it. Anyone know what's up?

 

91 octane mode
Yes if you do not run 91 or above you will develope a tick, or worse.
If you were to try to download that tune to your truck it will tell you to run 91 or better.
Look on this fourm for the superchips thread it has everything you need to know.

BTW if you just sit there and play with your tunner you will find out alot, you can run 87 octane mode, take that tune off then try eco mode just as quick as it will let you.
Try everything you feel comfortable with change the settings on some tunes get a feel for your tunner

 

Run 91or higher in performance mode. You still get a little hp boost even on 87 mode. Personally I run 89 in 87 mode because I think 87 octane is poop. 91+ is just too damn expensive right now.