loooking at exhaust cat back systems.gibson seems like the only company to offer anything for the 4.2.what seems a little strange is sometimes they list also fits 4.6 and 5.4.mines a 2005 thanks for any replies in advance.

 

I have never looked at too many available options for ready-to-go systems, so I do not know what is offered.
I had a local shop do a basic system for both my 2000 and my 2005.
The cut the pipe behind the cat convertor, added pipe bent to fit, a SI/DO muffler and then bent-to-fit pipe out the rear.

You might want ot use the 'search' option for "exhaust" in this forum and see what you can find.
I seem to remember a few threads from days gone by.