when the manufacturer designed your/our vehicles the correct plugs/plug wires/ignition coils have been tested and matched ..
using non OEM parts in the ignition system with the very close fuel/timing controls now in use My opinion it would not be wise to mess with these parts..
to ensure MAX MPG checking the plug wire resistance and replacing plugs every 30,ooomi with oem irridium plugs should do it quite good..
air filter and cleaning the MAF sensor also should help.
at the 100,ooomi mark replace the upstream O2 sensor.
step on power pedal slowly...put a little extra air in the tires 2-3 psi..check often ...