I have a pretty nasty hole in my muffler, and my gas mileage has gone down. From 350+ per tank to around 300. The max also feels a little weaker. Could the leaky muffler be the culprit? I don't think I have been driving any more aggresive than normal.
I cleaned the throttle body last week. I have noticed my rpm idle is now slightly higher.

I have no engine mods.

 

Anyone??
:attention:

 

I don't think it should make a difference...a muffler only keeps the
exhaust quiet...and a hole would accomplish two things:

1) louder car
2) less back-pressure in the exhaust

So, my thoughts are "NO"...

hope this helps,
FLO_BOY

 

Exhaust leaks usually cost you horsepower and torque, but yours is far enough down the exhaust stream that it shouldn't cause much of a loss if anything...

I'd replace it anyway.