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8,170 Posts
whistle is normal due to the air filter.

I don't think you need to put it back to stock.

I would say, clean the filter, clean the air sensor.

Check the spark plug and see you MPG change.

The most I got from mine is 27 avg mpg and its like driving Ms. Daisy, most boring week of driving I ever had.

But my typical avg mpg is 20-22 mpg.
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