I bought a cat-less 2.5" turbo exhaust system for my '93, and it came with a downpipe, flex pipe and everything else behind. However, I'm confused since there are 2 bung holes for sensors; one on the downpipe and one right after the flexpipe. I'm assuming the DP one is for my wideband O2 sensor, but what could the other one be for?

 

Normally the one on your DP would be for your narrow band O2, the one further back for your WBO2.

 

Ah, it isn't necessary to run both is it? I'm planning on using a Megasquirt 2 PNP9093, not sure if it wants both.

 

You can plug the one you do not use.

 

Perfect, thanks a lot !!