Well you would need to edit the ships themselves for that.
Maybe then just go for like 20 instead of 40 crystals per stack.
Or edit the drop chance on salvaged parts.
Which might be the way I will edit it.
(Increase stack sizes but lower the drop rate per salvaged parts).
Which benefits then for the trading mechanic/stocks.

I gotcha, yeah a downside I see at the moment is with the increased stack size the pirate hauler's have a lot more on them so more income. Think i'll tweak their cargo capacity.

I like the crystals being a decent credit seller from scavenging though so you can just buy some materials.

But it's likely just me, I like high stack values haha. More stuff to haul

yeah but the crystal problem wouldn't be solved by that. The slots remain the same it's just much more output/value.
But if it works for you as you wanted, top ;)
Maybe for the selling issue I will increase the stack sizes a bit but have to see.
Originally it was intented to have a bigger cargo as requirement for those missions therefore more reward.

I just altered the file to also change the stack size of these two items.

It doesn't change how many crew take per trip, also the missile station itself still holds the 24 max for a load, just allows more ammo to be nearby I guess which can make it better for more prolonged fire over a longer fight which is what I wanted since i play on Commander Long Fights combat difficulty.

The Crystals being 5 per stack was just to low for me. Specially when killing the cargo ship it would drop a lot and fill almost 80% of my cargo just on these. Then selling them to a station was a nightmare because of the stacksize, they just wouldn't have room for them to sell. Making them 50 a stack helped a lot

I could additionally create another optional mod for increasing those if you want them also being affected. But yeah this was originally intented.

yeah that's intended.
Buffing ammo crew transport rate might be "op", since it effects in faster fire rates.
And crystals as mission reward should also remain the same at all settings.

Or crystals, them being 5 per stack normally

It looks like this doesn't increase the stack size of your Gadget Parts. Having only 24 a stack is filling up my ship so much, I need more! Haha.