more power from a 4.2
 

I have a 97 f-150 4wd with a 4.2 v6 I would like to get some extra power I want to pull a 14 ft car tralier now and then I want to put a exhaust on a air intake and not sure what else what rear end dose this have in it I would like to do a gear change to maybe 3.73s but dont want to lose all my gas mileage can I run true duals with out cats with out throwing a code any suggestions or advice would be great The truck was my dads before he passed away so geting a difirent one is not an option