I have one of these on my rear 02 sensor when I took my cat off(big mistake!!) I put a new cat converter back on the truck and now it runs just fine and sounds alot better.
Anyway, the truck runs like a champ, gets about 21MPG and no CE light. Would the MIL still somehow be affecting the truck in someway? Should I replace the rear 02 sensor or just leave it as is? -Mike-