How to change Fighter Costs?

[Fimbul]

I try to modify the build cost for Fighters, as I find the Metal increase rather extreme. So more hammer (because more sophisticated tech) compared to the metal. But it drives me nuts no matter what I change in the WEAPONS.lua it always remains the same. Fighter 1x cost, Bomber 2x cost and Strike Fighter 3x cost. Where is it then really defined?

-- cost_mult=2,
hammer_cost_mult=10,
metal_cost_mult=10,

That's what i tried. The changed description it applies, but not the cost changes. I tried the BM mod by Chasm and when I insert hammer_cost_mult and metal_cost_mult, then they are applied. Although another strange thing happened, when I just disabled his cost_mult=1.5, then the fighters got more expensive, especially metal wise.