There was no button for "reactivate and rehash an old, tired topic", because I am sure this is not a new question, but I had no success in the search tool, so it's new to me.
Working on a California car, 1999 NB1, that came with Cal ECU and exhaust, but also with the replacement Federal ECU, federal manifold, and a good system out the back of the car. So far, so good, so I started replacing parts. I found two sensors, one pre-cat (primary?), and one post-cat, on the down pipe (Secondary?). Only one provision will now exist, on the downpipe. I am planning on adding an AFM, so I know I will need a second port welded in.
Now the ask for advice part. Do I :
1. Go to an NB2 exhaust manifold, or stick with the elegant cast iron log? Goal is to remain SM legal.
2. Extend the primary, pre-cat O2 to reach the downpipe, then weld in a second bung six inches downstream of the first downpipe port? and what becomes of the second O2 sensor? With a federal ECU, does the need for the secondary, post-cat sensor go away?
3. Any other suggested items?
Thanks, as always. if sharing an old link for this info works, that'd be great.