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Discussion Starter #1 (Edited)
has anyone noticed a loss or gain in mpg after exhaust change from stock to performance muffler,mine use to show 18.6-19.2mpg at 60,taching 1600 rpm,s now the best has been about 16.3,,running 3.7 eng. 2"lift.265-70-17 tires,guess i need more back pressure, or something,also have air intake,2008 model
 

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Did you change the pipe diameter? Also did you reset the ecu.
 

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Discussion Starter #3
exhaust is still 2.5 in. have not reset ecu.,tryed a flowmaster 50,frist time why to loud,an sounded like a kids drifter car,when with a stock shorter less b-pressure an inside is almost noise free,wife didn,t notice,this is a 2wd, 307 gear road veh. only,first jeep ever to go back on fuel mileage,after modes, go figure?????????????
 

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I mean unless your pushin it harder cause you like the noise ;) but it shouldn't have dropped that much . I would reset the ecu and see how that goes.
 

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Discussion Starter #5 (Edited)
reset ecu,and reinstalled a heat sheild,will try that an see how that works
,just a cruiser,before all the changes, it would get 20.7,21.3 at 70,just didn"t think wheel"s/tires,would hurt that bad,my old cherokee4x4,3" lift,31" tires average,s a regular 19-19.3 at 73mph,figure that one out???????????
 

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The lift shouldnt really make it drop like that.. Unless it interfered with the great wind resistance of the Rolling Brick.. :sick: The only mod you did that resulted in the mileage drop was the Muffler though correct? you were doing well with mileage with the lift?
 

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Discussion Starter #7 (Edited)
The lift shouldnt really make it drop like that.. Unless it interfered with the great wind resistance of the Rolling Brick.. :sick: The only mod you did that resulted in the mileage drop was the Muffler though correct? you were doing well with mileage with the lift?[/quote]

that was mileage before lift,after lift average was 18.9 at 65 and 17,9-18.3 at 70. plus you add about a 3-4 mph faster with bigger tires,an an have to add 10 miles to ever100 miles traveled,just the muffler has affected the mileage will see on next trip,muffler installed correct also.
 

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Alright Yea sorry i couldnt be of more help. Let us know the updated mpg.
 
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