GenVibe - Community for Pontiac Vibe Enthusiasts

I was wondering if most people have had a decrease in their gas mileage after installing the Magnaflow cat-back exhaust. It seems that since I installed my exhaust ~2 months ago, my mileage has decreased about 3 mpg on average. I haven't driven any harder than I used to before the exhaust. I used to average 28-29 mpg combination city/highway, now I'm getting 25-26 mpg. After I installed the exhaust, I reset the ECU. Should the exhaust be causing this or can there be something else? About a month after I installed the exhaust, I changed my oil, checked all my tire pressures, rotated my tires, and cleaned my CAI filter. That did not affect anything, the mileage is still the same. I was also expecting my mileage to go up with the warmer weather as it always did in the past. Can you all with the Magnaflow's please tell me what kind of gas mileage you are averaging and did you see a decrease as well?Thanks,

I think my mileage actually went up a little. With an intake only, my best was 29mpg. I haven't caculated it too many times recently, but my best with my exhaust was 32mpg.

With my CAI I used to average 28-29 mpg and on road trips I usually got 32-33 mpg. I haven't taken any road trips since I put on the exhaust, but my everyday driving mileage has decreased.

I know mine has increased as well.

Mine has stayed about the same, maybe gone down slightly. 85% of my driving is in the city though so that might be the reason. I average about 26 mpg. The last long trip I took I averaged about 31 or so.

Does anyone think that a dirty MAF sensor may be causing worse gas mileage? I might inspect mine to seen what kind of condition it is in. Those of you that cleaned your's, have you noticed any changes?

Hi Justin,As soon as I cleaned mine, my idle went down about 200 rpm but now it's back to the same. Also, my Mileage this take-full has dropped some. I did the Acetone in the gas thing... http://forums.genvibe.com/zerothread?id=16375 so that's liable to be the issue there.No, I don't have a cat-back yet but that was my result from doing the cleaning.Dave

I noticed that my went down also. 2-3 mpg. I do mostly highway when not stuck in traffic. I was hoping for better mpg.