how should i fix a pipe leak

Try an exhaust shop first. They might be able to do it cheaper.

Straight pipes with a catalytic ? You can buy after market pipe/adapters/clamps at auto zoo crawl under there and jerk ball it together like I did many times with older vehicles where things seemed more accessible . for the time and money I just bring it to a muffler shop , But have at it if you want

If you have a Meineke (muffler shop) in your area try them. I've always had good luck with them. Including custom making exhaust pipes for cars that were older and had no pre bent pipes available. Hope that helps! Jim