Ever want to know how much Lower Mana Cost you can put on your suit before it hits a cap? Obviously 100% lower mana cost would be overpowered - you'd never run out or even use any. Well, you've come to the right place. Following is a list of what your caps are for your suit. Anything above what's listed is overkill, and a waste of those precious mods.
Hit chance increase - 45
Defense chance increase - 45
damage increase - 100
damage increase plus slayers - 200 (meaning 100 di plus repond slayer wep plus vermin slayer talisman is overkill for ratmen, a slayer gives 100% DI for those monsters who fall in that slayer category)
Swing speed increase - no hard cap*, soft cap** of 65 (depending on weapon, highest is soul seeker with 60, plus the 5 SSI on I think the Tourmaline ring)
hit mana/stamina/life leech - 100
hit point regeneration - 18 (only pertians to regen from items. hp regen from confidence or beast form or other "innate" abilities can go above this cap)
mana regeneration - 18 (same as for hp regen, only pertains to items)
stamina regeneration - 24 (same for hp and mana regen, only pertains to items)
strength - 125 real, 150 with items/potions
dexterity - 125 real, 150 with items/potions
intelligence - 125 real, 150 with items
lower reagent cost - 100
lower mana cost - 40
faster casting - 2 for all spells (magery/bushido/ninjitsu/spellweaving/necromancy) except for chivalry, which is 4
faster cast recovery - 6 for all spells of any skill
spell damage increase - 15 for pvp, no cap for pvm (soft cap with arties and max items is 76 I think)
lower requirements - 100%
hit point increase - no cap
stamina increase - no cap
mana increase - no cap
Enhance Potions - no cap (soft cap of 120 I think)
Luck - no cap (soft cap of 1485)
Reflect Physical - no cap (soft cap of 120 I think)
Skill bonuses - no cap
Did I miss any? I might have, this list is not all-encompassing and only contains what I was thinking of at the time.
*Hard cap refers to the cap put in place by the game mechanics. While you can design your suit to have 80 lower mana cost or more, it will only have the effectiveness of 40 lower mana cost, because that is the hard cap. Anything above that is a waste.
**Soft cap refers to how much of a mod you can put into your suit by finding/equipping all items with the highest amount of that particular mod. For example, luck has no hard cap, but the soft cap of 1485 is derived from 150 from the jester hat of chuckles (or the maritime reading glasses), 200 for the lucky necklace, 200 for the armor of fortune, 140 each from enhanced arms, legs, gloves and weapon, 100 each from bracelet and ring (preferrably the ring of the elements for resists), 80 from the vesper order shield, and 95 from the robe of the eclipse (or robe of the equinox). So 150+200+200+140+140+140+140+100+100+80+95=1485. That is the soft cap, and will remain so until such time as items come out that have higher luck than what is already out. Luck used to have a hard cap of 1200 but that has been since removed.
*Edit--Who stickied this for me?--Xare*