Trade it in.

I have found that old school V6's give you V8 mileage and 4 banger performance if you are lucky, lol.

Seriously, standard stuff, free flow exhaust, free flow air intake, good plugs, wires, cap/rotor, etc, are about it. There might be a computer "chip" that helps, but I know nothing about that. You might find that a turbo or supercharger would inprove your mileage, but I dunno.

They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.