· Satyr of the Midwest
Your buddy is an idiot. Search a little on these forums, as we've covered almost every conceivable exhaust setup known for these trucks. To the point, yes your truck should have two converter beds from the factory: the first is either a regular TWC (three-way catalyst) or reduction bed, the second a COC (conventional oxidation catalyst). Typical practice is to replace both with a single TWC rated for the vehicle's engine size and GVW.