neophyte

I have an 02 supercharged 4x4 frontier crew cab. I want to maximize its' ability to handle beach drive as I will use it for fishing. I've driven on the beach already. My traveling speed will be limited to 10 miles per hour. I know about required equipment, have a Co2 tank, staun tire deflators. What I'm interested in are things like mechanical upgrades etc that will assit me at the low end, not make gas mileage worse than it already is, and will not prevent hioghway uasage( I would also like to increase overall horsepower if possible). I've heard conflicting infromation on the effectiveness of things lie air intakes and cat backs.

Thanks,

Mark