2.3L ('02-'11) Ford Ranger 2.3L I4 Mods?

[avidrangerfan]

Hello! I'm new here so I apologise if this was already covered, but I was looking into possible mods for a (gasoline) 2.3L I4 Ranger (5-speed automatic) from 2002? For context, I'm from Europe and the Ranger is currently a project car, has less than 80k miles, mechanically sound and just has some body work to be done. Also, we have much stricter laws here regarding vehicle modifications, so I was hoping for some more discrete solutions for i.e. engine optimisation (gas mileage and/or power). Any and all help is very welcome!
Thank in advance!