Each to there own on mods. Personally I only like minor tasteful mods. I don’t think pinstadiums are needed in all cases. Depends if you put LED’s for your GI. I would start there but don’t color bomb it. Cool white for GI but can go brighter if needed. Color match inserts is generally OK. If that’s not bright enough you can look into pinstadiums. There is a fine line between a cool mod and just absolute gaudy. No alligator clips on any mods. Plug and play for any light up mods- no hack jobs.
If you are into sound upgrades look at Pin Woofer. Reviews of there products seem to be mostly good. Check out the club threads and you can get a lot of good insight to the mods for your games. Too many to list but the propeller mod for IJ may be a good one. Avoid hot gluing crap all over your games. And of course Color DMD is a great mod if you don’t have that. It’s probably the best single mod you can do that actually adds value to a game. You can also powder coat the armor (side rails, hinges, lock down bar etc.). The ideas for modding games is endless but start with the club threads for your games for ideas.
Speaker light kits/grill inserts are also simple mods that can add a nice touch.

Have fun…there your games so if you enjoy the mods that’s all that matters.