Currently have an 03 f150 with true dual exhaust with cats but no muffler. The truck is loud, but I'm looking for a deeper sound and am looking for suggestions. Possibly remove the cats?

 

Depending where you live, removing the cats can be an expensive fine. Going to more free flowing cats is an option There are many manufacturers who make them that will fit and work like normal. Get out Summit Racing or Jegs for these.

You need to check out some videos in YouTube to see who has a sound you like. And then find out what mufflers they used. Go to a truck meet locally to see what others are using. When you find one you like, talk to the owner to see what they used.