Add these to your GameUserSettings.ini file, you only need to add the ones you want to edit. If you don't add one it will default to what the listed vaules below are set to. If you set the weight of an item to 0.0 then it will default back to the below value.

Values below are the DEFAULT stack mod values.

[100kStackResources]
AmmoniteBloodSize=100000
AnglerGelSize=50000
ApexDropAlloSize=25000
ApexDropAlphaCarnoSize=25000
ApexDropAlphaLeedsSize=25000
ApexDropAlphaMegalodonSize=25000
ApexDropAlphaMosasaurSize=25000
ApexDropAlphaRaptorSize=25000
ApexDropAlphaRexSize=25000
ApexDropAlphaTusoSize=25000
ApexDropArgentavisSize=25000
ApexDropBasiloSize=25000
ApexDropBoaSize=25000
ApexDropFireWyvernSize=25000
ApexDropGigaSize=25000
ApexDropLightningWyvernSize=25000
ApexDropMegalaniaSize=25000
ApexDropMegalodonSize=25000
ApexDropPoisonWyvernSize=25000
ApexDropRexSize=25000
ApexDropSarcoSize=25000
ApexDropSauroSize=25000
ApexDropSpinoSize=25000
ApexDropTherizSize=25000
ApexDropThylacoSize=25000
ApexDropTusoSize=25000
ApexDropYutySize=25000
BeerSize=1000
BlackPearlSize=100000
CharcoalSize=100000
ChitinSize=100000
ChitinOrKeratinSize=100000
ChitinPasteSize=100000
ClaySize=100000
CrystalSize=100000
DeathwormHornSize=25000
ElectronicsSize=100000
ElementSize=50000
ElementShardSize=100000
FibersSize=100000
FlintSize=100000
GasolineSize=100000
GunpowderSize=100000
HairSize=100000
HideSize=100000
HornSize=25000
KeratinSize=100000
LeechBloodSize=50000
MetalSize=100000
MetalIngotSize=100000
ObsidianSize=100000
OilSize=100000
PeltSize=100000
PeltOrHairSize=100000
PolymerSize=100000
PolymerOrganicSize=100000
PreservingSaltSize=25000
PropellantSize=25000
SquidOilSize=100000
RareFlowerSize=100000
RareMushroomSize=100000
RawSaltSize=100000
SandSize=100000
SapSize=100000
SiliconSize=100000
SilkSize=100000
SnailPasteSize=100000
SparkpowderSize=100000
StoneSize=100000
SubstrateAbsorbentSize=100000
SulfurSize=100000
ThatchSize=100000
WoodSize=100000
WoolSize=100000
AmmoniteBloodWeight=0.0015
AnglerGelWeight=0.0015
ApexDropAlloWeight=0.005
ApexDropAlphaCarnoWeight=0.005
ApexDropAlphaLeedsWeight=0.005
ApexDropAlphaMegalodonWeight=0.005
ApexDropAlphaMosasaurWeight=0.005
ApexDropAlphaRaptorWeight=0.005
ApexDropAlphaRexWeight=0.005
ApexDropAlphaTusoWeight=0.005
ApexDropArgentavisWeight=0.005
ApexDropBasiloWeight=0.005
ApexDropBoaWeight=0.005
ApexDropFireWyvernWeight=0.005
ApexDropGigaWeight=0.005
ApexDropLightningWyvernWeight=0.005
ApexDropMegalaniaWeight=0.005
ApexDropMegalodonWeight=0.005
ApexDropPoisonWyvernWeight=0.005
ApexDropRexWeight=0.005
ApexDropSarcoWeight=0.005
ApexDropSauroWeight=0.005
ApexDropSpinoWeight=0.005
ApexDropTherizWeight=0.005
ApexDropThylacoWeight=0.005
ApexDropTusoWeight=0.005
ApexDropYutyWeight=0.005
BeerWeight=0.002
BlackPearlWeight=0.0015
CharcoalWeight=0.0015
ChitinWeight=0.0015
ChitinOrKeratinWeight=0.0015
ChitinPasteWeight=0.0015
ClayWeight=0.0015
CrystalWeight=0.0015
DeathwormHornWeight=0.008
ElectronicsWeight=0.0015
ElementWeight=0.0015
ElementShardWeight=0.0015
FibersWeight=0.0015
FlintWeight=0.0015
GasolineWeight=0.0015
GunpowderWeight=0.0015
HairWeight=0.0015
HideWeight=0.0015
HornWeight=0.008
KeratinWeight=0.0015
LeechBloodWeight=0.0015
MetalWeight=0.0015
MetalIngotWeight=0.0015
ObsidianWeight=0.0015
OilWeight=0.0015
PeltWeight=0.0015
PeltOrHairWeight=0.0015
PolymerWeight=0.0015
PolymerOrganicWeight=0.0015
PreservingSaltWeight=0.0015
PropellantWeight=0.0015
SquidOilWeight=0.0015
RareFlowerWeight=0.0015
RareMushroomWeight=0.0015
RawSaltWeight=0.0015
SandWeight=0.0015
SapWeight=0.0015
SiliconWeight=0.0015
SilkWeight=0.0015
SnailPasteWeight=0.0015
SparkpowderWeight=0.0015
StoneWeight=0.0015
SubstrateAbsorbentWeight=0.0015
SulfurWeight=0.0015
ThatchWeight=0.0015
WoodWeight=0.0015
WoolWeight=0.0015

[100kStackAmmo]
GasGrenadeSize=500
PoisonGrenadeSize=500
TekGrenadeSize=500
AlarmTrapSize=500
BolaSize=500
C4AmmoSize=1000
ClusterGrenadeSize=500
FlareGunSize=500
GrenadeSize=500
PoisonTrapSize=500
SpearSize=50
TripwireC4Size=500
AdvancedBulletSize=1000
AdvancedRifleBulletSize=1000
AdvancedSniperBulletSize=1000
AggroTranqDartSize=1000
ArrowFlameSize=1000
ArrowStoneSize=1000
ArrowTranqSize=1000
BallistaArrowSize=500
BoulderSize=500
ChainBolaSize=500
CannonBallSize=100
CompoundBowArrowSize=1000
FlamethrowerAmmoSize=1000
GrapplingHookSize=1000
RefinedTranqDartSize=1000
RocketSize=1000
RocketHomingMissileSize=1000
SimpleBulletSize=1000
SimpleRifleBulletSize=1000
SimpleShotgunBulletSize=1000
TranqDartSize=1000
TranqSpearBoltSize=1000
GasGrenadeWeight=0.5
PoisonGrenadeWeight=0.5
TekGrenadeWeight=0.5
AlarmTrapWeight=0.5
BolaWeight=0.5
C4AmmoWeight=0.1
ClusterGrenadeWeight=0.5
FlareGunWeight=0.5
GrenadeWeight=0.25
PoisonTrapWeight=0.5
SpearWeight=3.0
TripwireC4Weight=0.5
AdvancedBulletWeight=0.1
AdvancedRifleBulletWeight=0.1
AdvancedSniperBulletWeight=0.2
AggroTranqDartWeight=0.2
ArrowFlameWeight=0.2
ArrowStoneWeight=0.2
ArrowTranqWeight=0.2
BallistaArrowWeight=0.4
BoulderWeight=1.5
ChainBolaWeight=20.0
CannonBallWeight=5.0
CompoundBowArrowWeight=0.4
FlamethrowerAmmoWeight=0.1
GrapplingHookWeight=0.25
RefinedTranqDartWeight=0.2
RocketWeight=0.1
RocketHomingMissileWeight=0.1
SimpleBulletWeight=0.1
SimpleRifleBulletWeight=0.1
SimpleShotgunBulletWeight=0.1
TranqDartWeight=0.2
TranqSpearBoltWeight=0.4

[100kStackConsumables]
BerryAmarberrySize=50000
BerryAzulberrySize=50000
BerryMejoberrySize=50000
BerryNarcoberrySize=50000
BerryStimberrySize=50000
BerryTintoberrySize=50000
BloodPackSize=25000
BugRepellantSize=100
CactusSapSize=100000
CookedLambChopSize=25000
CookedMeatSize=25000
CookedMeatFishSize=25000
CookedMeatJerkySize=25000
CookedPrimeMeatSize=25000
CookedPrimeMeatFishSize=25000
CookedPrimeMeatJerkySize=25000
CureLowSize=1000
HealthPotionHeal=0.25
HealthPotionCooldown=5.0
JellyVenomSize=50000
NarcoticSize=100000
RawMeatSize=50000
RawMeatFishSize=50000
RawMeatMuttonSize=50000
RawPrimeMeatSize=50000
RawPrimeMeatFishSize=50000
SeedDefensePlantSize=50000
SpoiledMeatSize=50000
StimulantSize=100000
SweetVeggieCakeSize=10000
VeggieCitronalSize=25000
VeggieLongrassSize=25000
VeggieRockarrotSize=25000
VeggieSavorootSize=25000
WyvernMilkSize=1000
BerryAmarberryWeight=0.001
BerryAzulberryWeight=0.001
BerryMejoberryWeight=0.001
BerryNarcoberryWeight=0.001
BerryStimberryWeight=0.001
BerryTintoberryWeight=0.001
BloodPackWeight=0.0005
BugRepellantWeight=0.001
CactusSapWeight=0.001
CookedLambChopWeight=0.001
CookedMeatWeight=0.001
CookedMeatFishWeight=0.001
CookedMeatJerkyWeight=0.001
CookedPrimeMeatWeight=0.001
CookedPrimeMeatFishWeight=0.001
CookedPrimeMeatJerkyWeight=0.001
CureLowWeight=0.001
JellyVenomWeight=0.001
NarcoticWeight=0.001
RawMeatWeight=0.001
RawMeatFishWeight=0.001
RawMeatMuttonWeight=0.001
RawPrimeMeatWeight=0.001
RawPrimeMeatFishWeight=0.001
SeedDefensePlantWeight=0.001
SpoiledMeatWeight=0.001
StimulantWeight=0.001
SweetVeggieCakeWeight=0.06
VeggieCitronalWeight=0.001
VeggieLongrassWeight=0.001
VeggieRockarrotWeight=0.001
VeggieSavorootWeight=0.001
WyvernMilkWeight=0.001
BerryAmarberrySpoil=600.0
BerryAzulberrySpoil=600.0
BerryMejoberrySpoil=600.0
BerryNarcoberrySpoil=600.0
BerryStimberrySpoil=600.0
BerryTintoberrySpoil=600.0
BloodPackSpoil=1800.0
BugRepellantSpoil=18000.0
CactusSapSpoil=600.0
CookedLambChopSpoil=4050.0
CookedMeatSpoil=1200.0
CookedMeatFishSpoil=1200.0
CookedMeatJerkySpoil=172800.0
CookedPrimeMeatSpoil=1200.0
CookedPrimeMeatFishSpoil=4050.0
CookedPrimeMeatJerkySpoil=172800.0
CureLowSpoil=12000.0
HoneySpoil=1200.0
JellyVenomSpoil=2700.0
RawMeatSpoil=600.0
RawMeatFishSpoil=1200.0
RawMeatMuttonSpoil=560.0
RawPrimeMeatSpoil=140.0
RawPrimeMeatFishSpoil=280.0
SpoiledMeatSpoil=900.0
SweetVeggieCakeSpoil=4800.0
VeggieCitronalSpoil=300.0
VeggieLongrassSpoil=300.0
VeggieRockarrotSpoil=300.0
VeggieSavorootSpoil=300.0
WyvernMilkSpoil=1800.0

[100kStackSeeds]
SeedAmarBerrySize=1000
SeedAzulBerrySize=1000
SeedMejoBerrySize=1000
SeedNarcoBerrySize=1000
SeedStimBerrySize=1000
SeedTintoBerrySize=1000
SeedCitronalSize=1000
SeedLongrassSize=1000
SeedRockarrotSize=1000
SeedSavorootSize=1000
SeedCarnivorousPlantSize=1000
SeedPlantSpeciesYSize=1000
SeedPlantSpeciesZSize=1000
SeedAmarBerryWeight=0.001
SeedAzulBerryWeight=0.001
SeedMejoBerryWeight=0.001
SeedNarcoBerryWeight=0.001
SeedStimBerryWeight=0.001
SeedTintoBerryWeight=0.001
SeedCitronalWeight=0.001
SeedLongrassWeight=0.001
SeedRockarrotWeight=0.001
SeedSavorootWeight=0.001
SeedCarnivorousPlantWeight=0.001
SeedPlantSpeciesYWeight=0.001
SeedPlantSpeciesZWeight=0.001

[100kStackAbAmmo]
GlowStickSize=500
ZiplineSize=500
GlowStickWeight=0.05
ZiplineWeight=0.05

[100kStackAbConsumables]
AggeravicMushroomSize=50000
AquaticMushroomSize=50000
AscerbicMushroomSize=50000
AuricMushroomSize=50000
NamelessVemonSize=500
PheromoneGlandSize=10000
AggeravicMushroomWeight=0.001
AquaticMushroomWeight=0.001
AscerbicMushroomWeight=0.001
AuricMushroomWeight=0.001
NamelessVemonWeight=0.01
PheromoneGlandWeight=0.01
AggeravicMushroomSpoil=25920.0
AquaticMushroomSpoil=300.0
AscerbicMushroomSpoil=600.0
AuricMushroomSpoil=600.0
NamelessVemonSpoil=1800.0

[100kStackAbResources]
ApexDropBasiliskSize=25000
ApexDropBasiliskAlphaSize=25000
ApexDropCrabClawSize=25000
ApexDropReaperBarbSize=25000
ApexDropRockDrakeSize=25000
ElementOreSize=100000
FungalWoodSize=100000
GasBallSize=50000
GreenGemSize=100000
BlueGemSize=100000
RedGemSize=100000
ApexDropBasiliskWeight=0.02
ApexDropBasiliskAlphaWeight=0.02
ApexDropCrabClawWeight=0.02
ApexDropReaperBarbWeight=0.02
ApexDropRockDrakeWeight=0.02
ElementOreWeight=0.002
FungalWoodWeight=0.002
GasBallWeight=0.005
GreenGemWeight=0.002
BlueGemWeight=0.002
RedGemWeight=0.002

[100kStackAbWeapons]
ClimbPickDurabilityDecreaseMultipler=0.2

[100kStackAbArmor]
FlyingRelicSpeedMin=0.1
FlyingRelicSpeedMax=1.0

[100kStackWeapons]
MetalHatchetHarvestAmount=1.25
MetalPickHarvestAmount=1.25
MetalHatchetDurabilityDecreaseMult=1.0
MetalPickDurabilityDecreaseMult=1.0

[BigStackExtAmmo]
TekGravityGrenadeSize=500
CannonShellSize=500
RocketPodSize=500
TekGravityGrenadeWeight=0.05
CannonShellWeight=0.05
RocketPodWeight=0.05

[BigStackExtResources]
ApexDropGasBagSize=25000
BlueCrystalizedSapSize=100000
CondensedGasSize=100000
CorruptedNoduleSize=25000
FungalWoodSize=100000
ElementDustSize=100000
UnstableElementSize=100
FragmentedGreenGemSize=100000
CongealedGasBallSize=100000
CorruptHeartSize=25000
RedCrystalizedSapSize=100000
ScrapMetalSize=100000
ScrapMetalIngotSize=100000
UnstableElementShardSize=100
SilicateSize=100000
ApexDropGasBagWeight=0.002
BlueCrystalizedSapWeight=0.001
CondensedGasWeight=0.001
CorruptedNoduleWeight=0.002
FungalWoodWeight=0.001
ElementDustWeight=0.001
UnstableElementWeight=0.001
FragmentedGreenGemWeight=0.001
CongealedGasBallWeight=0.001
CorruptHeartWeight=0.002
RedCrystalizedSapWeight=0.001
ScrapMetalWeight=0.001
ScrapMetalIngotWeight=0.001
UnstableElementShardWeight=0.001
SilicateWeight=0.001

[100kStackGenResources]
AmbergrisSize=10000
TurtleShellSize=100000
AmbergrisWeight=0.05
TurtleShellWeight=0.001

[100kStackStructures]
CampfireCraftSpeed=5.0
CharcoalBakerCraftSpeed=2.5
ElementCrafterCraftSpeed=5.0
ForgeCraftSpeed=5.0
IndustrialForgeCraftSpeed=5.0
IndustrialGrillCraftSpeed=5.0
PreservingBinCraftingSpeed=10.0
ChemBenchCraftSpeed=5.0
FabricatorCraftSpeed=5.0
IndustrialCookerCraftSpeed=5.0
MortarCraftSpeed=5.0
TekReplicatorCraftSpeed=5.0
SmithyCraftSpeed=5.0
CampfireDisableText=False
CharcoalBakerDisableText=False
ElementCrafterDisableText=False
ForgeDisableText=False
IndustrialForgeDisableText=False
IndustrialGrillDisableText=False
PreservingBinDisableText=False
ChemBenchDisableText=False
FabricatorDisableText=False
IndustrialCookerDisableText=False
MortarDisableText=False
SmithyDisableText=False
AutoTurretSize=500
HeavyTurretSize=500
BallistaTurretSize=500
CatapultTurretSize=500
MinigunTurretSize=500
RocketTurretSize=500
TekTurretSize=500
SmallFloatingIslandHealth=500000
SmallFloatingIslandUsesHealth=False
LargeFloatingIslandHealth=1250000
LargeFloatingIslandUsesHealth=False
SmallFloatingPlatformHealth=500000
SmallFloatingPlatformUsesHealth=False
LargeFloatingPlatformHealth=1250000
LargeFloatingPlatformUsesHealth=False

[100kStackEngramUnlocker]
DisableVanilla=False
DisableSorchedEarth=False
DisableAberration=False
DisableExtinction=False
DisableGenesis=False
DisableTek=False