I have a 2003 F-150 XL 4.2v6 and I wanted to put straight pipes on it, but keep the catalytic converter. Any suggestions on what to do?

 

lol get ear plugs first. i had a magnaflo offroad shorty on my old truck and i had to wrap it with header wrap just to talk to the wife without yelling. but as a note of caution strait from cat back might not have enough back pressure. mine idled like crap when we only put a strait pipe on it.

 

Your 4.2 has 2 cats in a "Y" pipe. You may want to consider a free flow muffler with a dual outlet so you will still have 2 tail pipes. Loud pipes on a 6 cyl. doesn't sound good.
And as dlbb said, it won't idle right w/straight pipes. In fact it will idle like a paint shaker.

AND, welcome to the forum!

 

Thank you both for help.