I am probably going to get a test pipe as I am looking for a louder exaust note and don't want to change out the exaust. I researched a bunch of threads and found everyones opinions clashed. I just want to put on the test pipe and an intake in.

 

A test pipe is just a hollow tube that replaces the catalytic converter. You may get very slight variations from the material used to construct this pipe, but a hollow tube is a hollow tube unless you start adding lumps and bumps to it. Not much science involved here. You're trying to read far too much into things.

Oh, did you know that you'll need to find some way of fooling the ECU once the O2 sensor is gone or changed position?

 

a better question would be....
Q: Do all Test Pipes smell the same?
A: Yes, it's going to make the air you breath around you more STINKY!