Exhaust leak

Hello,

From what you are describing it sounds like you do have an exhaust leak. Unfortunately, in order to locate the leak you will have to inspect the exhaust joints, which will require you to be under the vehicle. Typically, when the exhaust leaks you will feel puff of air coming out of the leak (with the engine running). It is a good idea to check for leak when the engine / exhaust is cool.
For the most part when there is a leak it is easy to detect if you get close enough to it. As the noise will be obviously noticeable.

If you had the converter installed at a shop, I would suggest taking it there as it should not leak after they have done the installation.

Please let me know of any questions.
Thank you.

https://www.2carpros.com/articles/how-exhaust-systems-work