Should I pay to replace my entire catalytic converter, or just weld it?

About 2ish weeks ago, I started hearing a really loud noise coming from my car (Nissan Sentra 2011) that got even louder when I accelerated. In more recent days, I’ve also had a problem where my RPM fluctuates, and one one while driving my car started to jerk forward and act as if I was pumping the brakes, so I had... show more About 2ish weeks ago, I started hearing a really loud noise coming from my car (Nissan Sentra 2011) that got even louder when I accelerated. In more recent days, I’ve also had a problem where my RPM fluctuates, and one one while driving my car started to jerk forward and act as if I was pumping the brakes, so I had to pull off the road. I had it checked out by my mechanic, who said my dual converter system was rotting off. They said it’d be about $1,200 to fix. I am a teenager working minimum wage and paying on car payments and car insurance, so needless to say this is a lot for me to pay. I took it to a different mechanic some family friends recommended and they told me that if it was only a specific piece of the catalytic converter rotting off, they could just cut it off and weld a new piece on for $40-80. The whole converter looks rusty, though. Should I just replace the entire thing or just pay the $40-80!? How reliable is this? Thank you.
5 answers 5