[mark houghton]

Originally Posted by Tippy

You want it after the turbo and before the muffler.

Ideally, yes, to prevent possible lean reading due to ambient air if installed post-muffler as mine was. Some discussion and concern has been voiced about the sensor withstanding the higher exhaust temps when installed pre-muffler, so I eventually chose the safer route (for sensor longevity). For what it's worth, I never had any issues.