Personally any mods are fine as long as they are reversable (easily).

If you find yourself in a funk with your pins why not try extra rubbers or added wires or plastic parts secured by current playfield parts. sounds like a groovy idea.

Adding a center post to a game designed not to have one, is like putting training wheels on your dirtbike.

pretty sure PAPA does that all the time for high-level tournaments.

another cheater example: my local Op got a Harlem Globetrotters that someone put a post between the two left flippers to prevent getting double flipper bitched. He removed it first thing.

This is ok, yep

I removed the control gate to iron hide on TFLE. Best thing I ever did to that game.

Remove the ball. That'l change things

I don't own TFLE anymore, but removed the control gate from the IH mini pf makes it so the ball can't get trapped up there. Allows faster gameplay and makes playing the IH mode a challenge.

I took the upper left orbit gate out of WPT, per the suggestion of the designer. Many others have done so as well.

I also added a deflector to the POTD exit in LOTR. Even though Keefer maintains the random dropping ball design was intentional, I far prefer the smoother/faster flow and prevention of ugly bounces, playfield dings, broken plastics etc. to scoring a few inconsequential souls if the ball bounces into the shire.

I'm all in favor of people altering games. It doesn't matter if you make the game easier or harder, as long as you find it to be more fun. For example, I did the post mod on my TZ. This prevents the ball from bouncing out of the rocket. To me, this makes the game much more enjoyable. I would, however, caution against performing any mods that do irreversible damage to the playfield (i.e. adding a post between the flippers). In the case of my TZ mod, the game can be easily reverted back to its original configuration.

A flipper post is reve3rsible. There's just a tiny, insignificant hole there when removed.

I removed the post and rubber ring in the pops of WH2O that keep the ball in the pops opposed to letting it go towards the right outlane. There is a switch over there that is impossible to hit with the rubber there so seems like the ring was just added to make the game a little less punishing out of the pops.