I have a 1997 Suburban with a vortec 350. I'm thinking of removing the catilytic converters out of the exhaust system. I have the OBD2over ride, or MIL Eliminator for the truck. Fuel mileage wise, I've heard it will increase and others say it will decrease. Does anyone has any comments on the subject?

 

Depending on where you live the fuel usage may not be the issue. In some states where the vehicle must be inspected annually removing the converters may not be such a good idea.
The performance nuts I know around here tell me if it has an O2 sensor after the converter don't remove it.