Loss of MPG with new Exhaust

[Mudfever]

I have the 5.3 and put a drop in K&N filter and had a glasspack put on that is dualed out the back. I ordered a SI/DO, but when I got it, the louver's(sp) faced the DO side (meaning the pack is on backwards).

Stock, I was getting 14-15 MPG in town. Now 2 months after I put the filter and exhaust on, I am getting 11-12 MPG. I didn't check it right after (was driving to hear), but now for the last 2 tanks, I have taken it pretty easy (RPM under 2,500).

Could the pack being on backwards be a problem?

Or, what do you think it could be?

Thanks,

Jason

[xx_ED_xx]

Wheres the old exhuast?

[Quyonmob]

Are you driving like a tool now that you have noisy pipes? I know I did for a month or two...mpg went back to normal after "rackin da pipes" lost its novelty.

[javi05]

yep new muffler will do that.. you tend to step on it more and more.. i know i do. and now with this custom tune.. i step on it even more.. i love it. your mpg's should go back down after you get used to the sound.

[TOOTHPICKPIMPIN]

Amen

[dropped94]

Or if you over oiled your k&n try taking off your maf and clean it with contact cleaner, and quit "rackin da pipes" lol

[Sierra H/O]

Are you driving like a tool now that you have noisy pipes? I know I did for a month or two...mpg went back to normal after "rackin da pipes" lost its novelty.
I seem to have that same problem from time to time:naughty:

[Mudfever]

but now for the last 2 tanks, I have taken it pretty easy (RPM under 2,500).

Could the pack being on backwards be a problem?

Or, what do you think it could be?

Thanks,

Jason

See above, I am taking it easy. And I didn't oil the filter, It said it was pre-oiled. Was I supposed to get oil with it?

Thanks

[CoreyZ71Sierra]

Was there a change in the wheather? I know in the fall i was getting better stock than i am now with a intake and duals in the winter. The winter grade fuel can do that. Even a different brand of gas can change things.

[CoreyZ71Sierra]

Was there a change in the wheather? I know in the fall i was getting better stock than i am now with a intake and duals in the winter. The winter grade fuel can do that. Even a different brand of gas can change things.

[RICK98Z]

Yeah with winter my mpg takes a dump on me too. I think it is the winter fuel. It can't hurt to get a can of MAF sensor cleaner and spray that as well. Sometimes the intake can pull a little of the oil up into MAF so go ahead and clean it as a start. And drive like grandma to see how the mpg's go but unfortunately sometimes exhaust hurts more than it helps in the mpg area. That is why I haven't purchased an exhaust yet because I have a 6.0l lifted crewcab that get about 10mpg now, I'm scared my mpg will take another drop with duals!