I got in an accident about a year ago and it jacked up my A pipe in my exhaust (the part that takes the headers from 2->1), I replaced it with a cheap ass something, and same deal with the cat (cheap), and put in a Bosch O2 sensor.
Other then that it’s completely stock Honda exhaust

Since then MPG has been on the suckie side, and I think the cause might have to do something with the fact that each pipe in the "OES" pipe is 1/4 inch smaller then stock (that is the two pipes that go to 1 are 1/4 inch smaller EACH).

Could this be the cause? it’s taken me a long time to put 2 and 2 together. Also I think its running a little rich, as my tail pipes are covered in black soot.

PS its an EX so I’m rocking the 4-2-1’s

 

Might be...kinda makes a little bit of sense.

 

its my birthday, so im bumping this.... yay for 20.. i hate teenagers

 

Check for exhaust leaks and I would go with NTK for O2 sensors. Bosch and Hondas don't mix very well. Take your car to a car tuner and have them put on a wideband O2 sensor and do some runs. They'll definitely be able to tell you what the lambda is. You might also want to check the condition of the plugs.

 

i thought bosch was good? so ntk it is...

 

Anything related to spark or ignition, Honda's prefer OEM.