MagnaFlow's C4 systems come in two versions. The early version (86-91) features 2.5" fast-flowing mandrel-bent stainless steel tubing and comes with a high-flow after-cat Y-Pipe. The late version (92-96) features 3" mandrel-bent tubing and bolts to the factory Y-Pipe. Both system versions include a matched set of single-in, dual-out stainless steel MagnaFlow Performance Mufflers and polished, rolled edge, stainless steel tips. MagnaFlow's C4 systems have logged gains of 16.6 horsepower and 13.4 ft-lbs of torque on the dyno. Replace your failed OEM cat with a MagnaFlow Performance Converter and you'll see even better results.