Does taking the muffler off of a 97 Ford explorer 4.0 v6 reduce gas mileage?

Does taking the muffler off of a 97 Ford explorer 4.0 v6 reduce gas mileage? - 1

Possibly, but the main issues are with the noise & it may cause the check engine light to be lit… Leave the vehicle alone… It's not a race car

Hi no it increases the fuel used significantly,.

If you reduce the back pressure too much it's possible that can happen.

Seeing how the muffler is downstream from the cats, and downstream from any 02 sensors; removing the muffler *will not*

1. Cause any check engine light to come on.

2. Increase fuel usage in and of itself.

In most cases YES. This is due to it being part of a tuned system where back pressure is needed for good engine 'scavenging ' in cylinders to get best power. This is where exhaust gases flow out and assist drawing in new air charge. Engine will be set up for this amount of 'back pressure' and fuelling and spark advance set accordingly ( mapped)
removal normally has effect of heavily reducing back pressure an d thus full being injected doe snot have full at charge for efficient combustion so we get less power. Less power means we often push accelerator harder to compensate and get acceleration ( as will be much less) hence fuel consumption rises and can be significant! We will also get fault lights on dash as sensors 'see' an issue or other don't as not fitted to missing exhaust!