I have a question and thought. Over on the focus fanatics forum a guy came up with a cold air intake.
Link...
2012 Focus Custom Ram Air How-To - Focus Fanatics
People that have made the mod have seen a decent increase in highway mpg. It harms city driving mpg though. I think the city decrease in mpg makes sense based on some posts on here; Cold air causing the computer to add more fuel to keep the ratios in check.
The only thing I can come up with on the higher highway mpg is due to a possible positive/neutral pressure in the airbox. Could this be simulating a (very) low positive pressure turbo effect which has been discussed here on the forums? I plan on doing this and will do some a-b-a comparisons.
Any thoughts?