Not done any mods to improve power as I am happy with their designed output.
The triggers on the other hand benefit from a bit of TLC.
I have a colt and a 92 and on both I have removed the side plates to expose the trigger mechs. (careful there are springs in there, if you've not done it before do it in a clear plastic bag to catch the flying bits).
I then lubricate any bits that have a bit of pressure on them with Molybdenum disulphide grease applied with a jewellers screwdriver to the bearing surfaces and any slidy or swivelly bits I use gun oil from a pen oiler.
Refit the side plate and grips and cycle a few times to distribute the lubes and the trigger smooths out nicely. I have not yet seen the need to polish any components so don't know how much better you can make it. I would say that both mine were second hand and therefore presumably well "run in" by their previous owners.