Cavern of Souls ?

Coat of Arms : much faster then Door of Destinies . Gemhide Sliver : another mana producing sliver.

Comulative First Strike does nothing for you so I highly doubt you'll need 8 First Strikers.

Have you considered Legion Sliver instead of Door of Destinies ? Quite easy to cast with the mana producing slivers.Harmonic Sliver might be quite good.Homing Sliver works as a tutor for you. You won't need another Manaweft Sliver if you already have one in play. Tutoring might be good. Or Sliver Overlord if you don't feel like discarding... Again, wth the mana slivers this might be quite easy to cast.Horned Sliver is sort of mandatoy.Root Sliver ... At least as sideboard if you face any blue deck.Virulent Sliver if you add Horned Sliver . Poisonous is cummulative, btw.

How do you feel about infinite combos?

Last suggestion is Wild Pair . Most of your slivers can be easily looked for with this little enchantment. It does have a bit of a high cmc though.

Aluren and swarm 'em opponents!

I love Slivers +1 and Naya looks like the best colours. I know she is not a Sliver, but have you thought about putting in Aurelia, the Warleader ? That extra combat phase could help finish things off sooner. And if you tapped some Slivers for the mana to get her out, they would untap and join in the second combat.