I ran my HEMI always with 91 or 93 with the tune at 91 Performance tune. I was avg 17-18mpg highway even with the MT/Rs with I stayed under 72mph and 12-13 city with a heavy foot. My intake I cleaned constantly cause Im ocd about it. You really dont have to but with the wheeling, winter and constant city driving I like to keep it clean. Keep in mind I work from home and have down time where the filter can dry enough before putting the oil on.