The last 2 times i filled up i checked fuel milage and got 15.5 mpg both times,just did a e fan install and drove about 250 miles and filled back up and got 16.5 mpg this time over time it may be worth it i guess but after the 150 i spent on all the fan stuff it'll prolly take 6 months or more to brake even. I'll save 1 gallon to every 250 miles or so. 5000 miles thats 20 gallons saved. $150 worth of gas at 2.50 a gallon is 60 gallons so after 15000 miles it'll be worth it. As for performance cant tell anything over about 2500 rpm but under that it is a little more responsive. Just my 2 cents