Microlon treatment saves fuel by reducing internal friction. This also results in lower CHTs. The treatment also stops the piston rings locking in place, resulting in better sealing and higher compressions, thereby recovering more of the energy in the fuel, and reducing oil consumption. Microlon don't make a specific claim as to how much fuel you will, but it's usually at least 5% and sometimes nearer 10%. Even at 5%, this saving will pay more for the treatment on a 2000 hr TBO engine. Less fuel burnt is also better for the environment.
K&N Airfilters can save another 5%.
Airspeed Aviation can advise on both the above and are also dealers for Knots2U and can advise on the Gap Seals.