My weekend project was removing the catalytic converter and installing an M&K pre-muffler.
This is the culprit. I hate exhaust work. If I hadn't had an air chisel just getting the old one off would have taken half a day. All the bolts were rusted solid.
The old cat weighed 13lb 8 oz. The new M&K weighs 6 lb 7 oz. Seven pounds of ugly fat removed right where the car needed it.
Hard to imagine exhaust gasses actually getting through the cat. You can see clear through the M&K. The car should breath a lot easier now.
One of the bolts was rusted so tightly it had to be drilled out. The old bolts were SAE size mild steel. New bolts provided with the muffler are still SAE size, but they're stainless.
Looks a lot better back there now. Less heat, less bulk, less weight, and less restriction. The car is a bit louder, but not much. I haven't had a chance to get a seat -of-the-pants performance evaluation yet. The SW chip I installed last week was optimized for this muffler and 93 octane fuel.