Sorry to plague a forum with yet another cat-delete question. NOT looking to debate, just want the facts.
I have a 1999 Dakota 318 that I just did the Hughes plenum intake fix on. Definitely satisfied with the results, although I'll be even more satisfied if it lasts another 100k.
Anyway, during the 10,000 miles I probably put on this thing while it was sucking in oil, I'm assuming the cat has alot of buildup. During that 10,000 miles with a slight leak, I even needed a new upstream O2 sensor because it was fouled.
Also, on hot days with higher RPM I hear a pinball machine-like rattling coming from the exhaust, which I assume is broken chunks of catalyst.
My plan is to just buy a pipe with two female ends, weld in a bung (only downstream O2 is IN the cat), and cut out the cat and go.
I've heard testimonies of people who have simply relocated the downstream O2 like this and gotten no codes/CEL in older trucks.
Will I need a spark plug defouler? Will relocating the downstream O2 change ANYTHING fuel related? As long as it's hot I can't think of an issue, I'm aware that the upstream O2 is what the ECU uses for A/F ratio.
Again it is a 1999 5.2/318 with two O2 sensors, upstream and downstream.
This is my daily so I don't wanna F it up 🤣
Thanks!

 

On 99, you can ziptie the downstream to the framerail where it can get clear air but not burn anything or get clogged up