Post by
MidnightLamp »
https://forums.nicoclub.com/midnightlamp-u120178.html
Mon Nov 17, 2008 8:52 pm
I'd say try the search, but just for anyone else who stumbles on this:
A test pipe is a straight pipe or a resonator that is bolted in place of a Cat. It contains no pollution control mechanisms (the catalysts in a cat) and is used to reduce back pressure.
Usually, it's illegal to use for regular road driving, as the car doesn't have the pollution control provided by a cat, but it's definitely used anyways.