Ok, seems like im not getting what I'm supposed to be getting. IDk if I should post it in bug report. Lets see what our gurus will say about it, may be Im just not good at numbers.
Pic 1 no eng consoles equipped:

pic 2 i Neutronium:

Pic 3.

Any comments on that?
Thanx
Comments
So, using the formula:
Resistance = 1-(1/(1+total resist bonus))
1 console = 1-(1/1.15) = 13.04
2 consoles = 1-(1/1.3) = 23.07
3 consoles = 1-(1/1.45) = 31.03
4 consoles = 1-(1/1.6) = 37.50
Theoretical "maximum" would be 100% bonus, which would yield a 50% resistance to x. Looks to be directly in line with what you're seeing (give or take a smidge), which would mean the formula is very close to reality.
If you have a 50% bonus, you'd have 33.3% resist, which means it would take 50% more damage to destroy your hull (66% of damage gets through, so you have to do 1.5 times the damage for the same amount to get through)
If you have a 100% bonus, you have 50% resist, which means it takes 100% more damage to destroy your hull (50% of damage gets through, so you have to do twice the amount of damage for your hull to be destroyed.)
So, by increasing my resistance by 16.6%, my opponent has to do 50% more damage output for me to receive the same amount of damage to my ship. Doesn't look diminishing.
Now, for this to be "diminishing returns", each additional point of increase would need to yield less of an effect. However, the math would indicate that what we're seeing is a linear expression, as opposed to what would happen if it were directly added (which would be closer to an exponential curve, if you're really interested, I'll throw it up here). It helps to think that what they're calling "resistance" is the percent of additional damage that you'll be able to take, as opposed to the percentage of damage you'll resist.
Hope that helps and we are too recruiting!