Found gap size for Evo's but not the N/A 4B11...does anyone know what the gap should be for the GTS? I am doing a tune up this weekend.

 

Well im not sure what the gap for the gts is
I do know that the gap effects the voltage required to jump the arc. Bigger gap = more voltage, smaller = less voltage. The gap also effects the size or power of the spark bigger gap = more powerful spark, smaller gap = weaker spark.
Iridium & platinum plugs should only be gaped with wire gaping tool not the coin type. The coin type can destroy your expensive plugs.
What i recommend is getting some good quality copper plugs, plug gapper, dielectric grease & some anti-seize. Gap the plug .030-.035 & check & change them often, if the plug looks a little fouled just reduce the gap. You could also go as far as indexing your plugs if you want every bit of power out of your car.
if your not looking for performance & just want a low maintenance plug get iridium or platinum with a set gap. just my opinion tho & i cant believe mitsubishi doesnt have a spec for that
most important dont forget your lubes! & tighten beveled plugs 1/16th past hand tight 1/2 for gasket

add: another idea is the platinum 2/4 & gap each ground electrode differently hope this helps someone understand plugs a little better