ok this might sound dumb but. i need to know.
when i got a test pipe there were two big opening at the end of the pipe and one small one in the middle. i didnt install the test pipe so i have no clue about it. ok, that small opening in the middle, is that for the 02 sensor, or the o2 sensor is located on the headers manifold. ?

 

there should only be one hold at one end of the pipe for the O2 sensor. There are two sensors, one in the exhaust manifold and one right over the stock catalitic converter. Your saying theres two holes? Maybe you got the wrong pipe
Where did you get it? hope thise helps..

 

i got it from rrm. oh i was just wondering what was that middle whole was. its already installed in my car and it runs great. its just that when i see my headers. i see the o2 sensor and im left wondering what was that small round opening in my test pipe. is it another sensor.?

 

oh ok, yeah that extra hole is just for the O2 sensor. Our cars have two of them.

 

make sure that it was put in if its not u gonna have a nice hole in your exaust

 

Well it just makes for better flow, like an o2 elimantor that dumps!!! Yes it is true that is the bung for your 2nd 02 sensor. It wont hurt anything not having it in, maybe throw a CEL its the first one that you want to leave in.

 

what is cel

 

check engine light