From
This Thread over in bug reports, it was observed that, if you have Impact Mitigation 1, the "+150 armor" completely replaces the normal 5% of base armor minimum value for armor strength.
Hmm. Looking at the code, it's going to be whichever is higher - 5% of the ship's max armor (without the +150), or the modified effective armor rating at the point of impact (150 with IM, 0 otherwise). I'm still not 100% sure what I'm looking at as far as the pictures, but does this explain it?
This makes some sense to me - even with an Onslaught XIV with Armored Weapon Mounts and Heavy Armor, your base armor is still "only" 2425, and you'd need over 3000 base armor for the 5% minimum to be greater than 150.
(Even if I would have - like the people who reported this as a bug - have expected the minimum armor to be 5% of base + 150.)
What I'm curious about is how this interacts with Evasive Action 3. Would that Onslaught end up with a minimum armor strength of 225 (150 * 1.5), or 182 (2425 * .05 * 1.6)?
(And, posting this over here in discussion, because this question doesn't belong in the bug reports forum.)