Some slivers I suggest you consider are:
Hunter Sliver, Shadow Sliver, Venom Sliver, and Thorncaster Sliver
Also Training Grounds reduces the Overlord's ability to cost 1. Cryptic Gateway and Cavern of Souls ought to be in here as well.

what cards do you think i should take out

Is this meant for group or 1v1?

its more so made for multiplayer

Check out my list for ideas if you would like: Evolutions End

If you do end up using Shadow Sliver keep in mind that it makes it so that your slivers can only block other creatures with shadow. So either be able to survive, or able to kill all your opponents very fast.

All those slivers might be able to give you some ideas. Personally I think you're to creature heavy. Sliver decks are generally pretty strong when I play it's usually a race to take me out lol so you need things to help you with that

I would consider Artifact called Hivestone (allows beneficial creatures other than sliver to work in deck, and of course count as a sliver), as well something like Door of Destinies and or Coat of Arms (great if game is drawn out longer) +1/+1 stacking for each cast of sliver creature can replace Slivers with the ability to grant +1/+1 to Other sliver creatures... I find this combo great in EDH mainly cuz I can incorporate cards such as Archetypes as well as self hexproof providing creature types that are not Sliver type, with benefit of them gaining Sliver Type, and I may be mistaken but... I believe Hivestone adds Sliver to the Creature Types prior to casting to field of play(need verification on this) but if so it'd be an additional + to DoD, and Coat of Arms... (Sorry so long)

Leeching Sliver I'd say is a definate must have as well... (Defending player takes 1 dam for each attacking sliver) great cuz they take direct damage by just attacking regardless of being blocked...

what do you think i should take out for Leeching Sliver

Personally MasterXehanort I'd pull Megantic Sliver. Reason why is that if u plan to use deck for multiplayer I find great success keeping cost of casting slivers low. Plus to gain +3/+3 in my opinion is too costly land wise... Can gain larger buffs for half the cost and then still have enough land to cast another Sliver...( which is where the combo of Hivestone + Door of Destinies is great). With those u can run 1-3 drops Slivers all day and get great +1/+1 stax for board... Just some ways I like using Sliver Builds, hope info proves beneficial for ya!

Homing Sliver is nice backup for Sliver Overlord and can be nice if General gets sent back to CZ a few times...

O my idk how I miss not having Sentinel Sliver as well... Vigilance is of importance with Sliver in my opinion

I also run Adaptive Automaton and I find Belligerent Sliver to be incredibly useful for dwindling defenses.

Triumph of the Hordes halfs the amount of damage you have to do and makes dmg to creature permanent. Its a win condition card

Saw your post in Commander deck help, thought I'd add my 2 cents. First of all, cool looking sliver deck, +1. As far as recommending slivers go, ultimately I think that's entirely subjective to the player + you're running most of the clutch ones already. With that said, here's a few cards that have served me well in my own sliver build:

Others in the deck help thread have already made some solid recommendations as to what to cut, hopefully these cards give you a little food for thought. Good luck!

Prophet of Kruphix is the single most broken card you can run in Sliver Overlord decks. You get to play slivers during every opponent's turn as well as your own turn. I normally win the game in multiplayer the turn after I resolve that card.

You should run Intruder Alarm.

Quick explanation of why:

Prophet of Kruphix and Horned Sliver should also be looked at. Homing Sliver serves less and less purpose now that Sliver Overlord can't be tucked, so Horned Sliver could be an easy swap for that.

Drop Crop Rotation. You're not running Gaea's Cradle, which makes it less than satisfactory (also, if Crop Rotation gets countered, you still lose the land you sacrificed. Gaea's Cradle makes it worth that risk, but you're not running it, thereby making it 10 steps worse than it should be). Sylvan Scrying does a better job of just tutoring out lands like Cavern of Souls, Sliver Hive, etc..

Suggestions recap:

-Swap Crop Rotation for Sylvan Scrying (Rotation has a risk and you don't run the cards that make the risk worth it) or Nature's Lore, depending on what type of land you want to tutor out.

-Homing Sliver out for Horned Sliver. Tuck is no longer a thing, so Homing Sliver is significantly less useful than it used to be.

-Taurean Mauler or something else that's not so great out for Prophet of Kruphix or Quick Sliver, either of whom is nuts and should really need no explaining.

-Something, anything, out for Intruder Alarm, which basically lets you dump your whole library onto the battlefield and swing. I'd honestly run it over Descendants' Path any day.

Other Slivers to consider:

Hibernation Sliver, which is basically the only way you can dodge mass-exile. It may be worth looking into it over Mirror Entity, who only helps you when you're winning, while Hibernation Sliver can be relevant at many times due to your opponents running sweepers, removal that exiles, etc..

Psionic Sliver, who can let you kill at instant speed if you do the Intruder Alarm combo (and floating mana + Hibernation Sliver lets you do it as many times as necessary, to get around infinite life gain combos). Situational, though, and if you're okay with going to the combat step, wholly unnecessary.

Also, forgot to say:

Green Sun's Zenith > Worldly Tutor. Get you right to that Prophet of Kruphix for only 6 mana, no dealing with the top deck.

iv'e added three of the new duals from BFZ to the deck

Add original dual lands to make the deck more efficient. Also, there are multiple infinite mana combos you can add that would go well with Sliver Overlord and Sliver Queen.