It's hard to even imagine that rusted hulk next to the MagnaFlow catalytic Y-pipe could even have worked properly anymore. The chunks we found in the exhaust and a flow test confirmed that this system was garbage. Taking no chances, MagnaFlow installed all brand-new O2 sensors, instead of attempting to use the stock ones first.
2001 Ford F150 - Project Sinatra Part 4: Pavement Pounder