Low MPG

I have a 90 integra LS. It is stock except for GSR rims and 2" pipe. I seem to be getting 20 mpg shifting before 3000. I should be in the high twenties shouldn't I? What could be wrong? I did a tune up in October and use 89 octane city driving.

Been covered many times over. search. you'll find many answers.

shouldn't need to use 89, 87 is fine wont help just wasting $
do a tune up on teh car and check ur tire pressure

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