Anyone ever experience an increase in mpg when putting the silencer in their exhaust?

I know there are lots of variables, but I took my 98 SE on a road trip this weekend, had 5 people and a trunkload in the car and ran the AC the whole time. I wanted it to be a little quieter so I put the silencer in my cat-back system. I got the best gas mileage I can recall for my car (26.7)

I took it for a similar distance trip the weekend before with only 2 people (including myself) and the silencer out and only got around 24 mpg. Any scientific reason the silencer would increase efficiency?? Seems counter-intuitive.

 

how did you measure your mpg?

 

I always measure full tank to full tank. Reset the trip meter EVERY time I fill up and divide by how many gallons I put in.

 

from what i know it has to do wit backpressure...lesser backpressure=better mpg...but i don't knw how that would relate to your situation

 

Exactly, adding the silencer should reduce performance and efficiency. In reality, it probably does absolutely nothing in terms of measurable difference. That's why I scratch my head with this gas mileage improvement.

 

did a quick google search on back pressure n dis is wat i found

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