Time To Replace Exhaust

Hi. So I'm finally noticing some initial signs of knowing that I'll need to replace my entire exhaust system soon. Underneath the passenger side is some noticeable fluttering sounds of an exhaust leak. Has anyone replaced anything regarding exhaust on their X? Mine is a 2006 with 137000 miles. Considering the X was manufactured in 2005, everything is already basically 13 years old. Any advisement would be great. Whether I should just replace everything from the engine block back or to just replace the catalytic converters or replace them and the muffler and tail pipe. Also, what would you recommend for replacement parts too. Should I just go with all OEM parts or could i buy a performance cat-back and have that put on as well. Thanks.

Yes I know this is an old thread. I only get on here about once or twice a year... but this may help someone looking for a complete solution.

My 2000 Xterra, bought new (build date of May 1999), currently has 208,523 miles on it and still has the factory exhaust from the engine to the point the muffler bolts on! I have went through two mufflers and one O2 sensor in all that time. I am about to do the third muffler. I am going to buy just the muffler, tail pipe and clamps from these guys: https://www.carid.com/replacement-exhaust-kits.html

They do carry COMPLETE kits including the cats. Hope you have a cutting torch as getting exhaust bolts off is not going to happen!

Thanks - it's indeed helped! Now to get those bolts off - yeah!