I've used rampant for a while now, It's hand's down my favorite mod for Factorio ever, my problem is... it's not hard enough. I'm looking for how to change the files to turn it from pretty tough to defend some things, to fighting tooth and nail every second desperately trying not to be over run. At the moment, even with all the settings maxed out it's... not "end of days" enough for me. How can I make the waves larger than the default mod allows? How can I make the waves more frequent? I'm not interested in just giving 10x the hp to things, I want more things. I want what the mod offers, how the mod offers it, but like 5-10x the biters, and non stop raids/waves crashing into me. I know it'll impact the games cpu usage, If you tell me how to crank it to 13, I can tune it down to a 12 if my PC can't handle it.

You don't need to modify the mod for this. Just increase the biter base frequency and size during map generation (200% for death world setting, but you can go all the way to 600% for both) and also reduce pollution absorbtion by trees and terrain and pollution required to trigger attacks (50% on death world setting, but you can go all the way down to 10%).

you could always adjust the settings.lua by hand inside the zip and up the limit from 400 for attackWaveMaxSize.
Set the aggression modifier to 0 for disabling any kind of peace from the AI.

Just popping in to say this mod is still the only reason I like factorio. Thank you so much for keeping up with it!

Glad to hear you are enjoying the mod