The plugs i believe are near the exhaust manifold....
If you are unfamilliar with changing plugs you should not do it yourself
Because the plugs are near such high heat they are prone to fouling
Try to use NGK plugs and spring for the irridium
As you may already know never change plugs on a engine that is warm or hot. First thing in the morning stone cold is the best time to do it.
You can Google ask a Mitsubishi Tech on the web for further assistance
NGK platinum plugs
Six
Well the v6 engine will require you to take the intake off to get to the rear plugs but other than that it is pretty much the same
GAP:044
2002 galant , can't find the spark plugs
I USE BOSCH PLATINUM
3 just on top of the engine,u can see black cap with screw and wire,other 3 under the intake.
Four.
Front and middle spark plug.
0.7mm - 0.8 mm
You must remove the entire intake manifold for you to have access on the three spark plugs located underneath it. it is advisable that a qualified Mitsubishi technician should do this.
Once on 1-2 year on regular spark plugs. Once every there years on High end spark plugs.