exhaust on 3g and mpg

[bluebuggy]

i have a 03 Mitsubishi Eclipse gts
i want to put a exhaust on it.
every exhaust i looked at has a Straight Through (same as pipe) right??
so do i not need backpusure on the motor
and with a Straight Through exhaust will i lose my mpg

 

[super97gst]

i have a 03 Mitsubishi Eclipse gts
i want to put a exhaust on it.
every exhaust i looked at has a Straight Through (same as pipe) right??
so do i not need backpusure on the motor
and with a Straight Through exhaust will i lose my mpg

a straight through muffler is same size as the piping, yes. you do need some backpressure for the engine to operate efficiently. you will not lose fuel mileage from an exhaust, unless your car is completely stock and you install a gargantuan exhaust. most catbacks for your 03 will be fine. you should just go with a reputable company making a 2.5" catback unless you are intending to add forced induction in the future. if so you might consider going ahead with a full 3".