I think the 3 most important mods are:
Cut slots in the upper intake to break the scum on the top of the water
Remove ceramic rings but keep carbon & sponges,,sponges offer massive surface area for denitrification,, far more by volume than ceramic rings or Live Rock.
Install Maxi-jet 600 powerhead or similar (stock powerhead is 'rattly' and underpowered) and modify single-direction output of water from powerhead,,,the stock whirlpool water current is really annoying,, at least my clowns didn't like it.