I have a 1990 E-150 5.8L. EEC-IV. One HEGO located at the inlet to the cat. My cat clogged up and was cherry red when I stopped to investigate the smell.

When shopping for a new cat, the auto parts salesman stated I could just remove the cat and run the exhaust pipe straight to the muffler. He stated the cat did not affect anything since it was not monitored by a second O2 sensor at the outlet. He stated my van would run much better. I live in Tennessee, where emissions testing is not done.

However, I am curious, and would like a second opinion before doing anything. Maybe someone has done this before, or knows someone that has, or could advise as to the pros, cons.