don't trip we all learn. I had a bad muffler experience that cost me $300 just to weld on a $60 sebring muffler with a 3" tip. Not on the G of course.

By the end of the job the exhaust was pretty much dragging on the ground and the tip stuck out about 5 inches from the rear bumper. Within a week the piping was already rusting. Plus the guy gave me back the stock cat back spliced up in a about 10 equal pieces.

A couple years later I spent $200 to have some other guy put 2 different cannisters on the car with a custome Y split. He didn't do what I told him and made something like a sideways T split so one side was totally useless. The welds had leaks in them too. Much like your experience, he wanted to charge me another 150 to redo just that small section and the welds wouldn't even be matched up. He was going to backwards sleave the pipes together.

lol hope those stories make you feel better.