If you take the chrome piece you'll see two sets of welds. Reason for this is the small pipe runs within the muffler.
Yes you would want to cut a bigger hole and thru the small pipe. Some people have used a saws-all. It depends on you. I used a professional. Anyone who knows anything about metal is that welds are stronger than the metal it's holding together. That's stronger and harder to cut. So the guy who did mine carefully used a plasma cutter then a grinding wheel as to not make too big of a hole.
I hope that helps
Same here, plasma cutter and grinding wheel. Its a simple job for a professional welder.