2006 Chevy Silverado adding after market equipment

My p/u has a 6 liter gas engine 3.11 rear end also, I pull a ultra light weiight 5th wheel, loader over the scale is 6700 - 7000 lbs. I drive the about the speed limit 55 - 60. I live on the west coast, and drive from coast to Montana. I would like to increase the fuel efficiency. Would it be wise to put a new exhaust system and a new intake filter system, and a chip. I don't want to lose any power maybe gain a little but increase gas mileage. The thing I do not want to do is hurt the pickup or the engine. I am retired and know little about these things. Is it something I could do my self or should it be done by an expert? Thanks mike