does the harley f150 use premium or regular gas in stock form? referring to the supercharged models, such as 2003. i am mid swap on my 2003 expedition, and was hoping to have one of my 3 tunes able to run on regular 87 octane gas.

 

Premium......

 

Absolutely the best premium gas you can get especially if you are adding a 6lb lower like your sig says.
Don't even consider 87 or 91 but when you order a tuner, get a "bad gas" tune in case you ever fill up with a tank of garbage.
I got my tunes from Troyer Performance and am very happy with them.