You gotta look at it from a cost stand point to. Intake and exhaust may get you maybe 1 mpg more. but the cost for that extra mpg is rediculous. What you could do is replace your tires with Lrr tires when the time comes, switch to 0w-20 motor oil, etc. I dont have the new focus but I have a fiesta. So I do plan on switching to better tires when the time comes.
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