Ambush feats: Stacking?

[D&DPrinceTandem]

I am building a poisoned based character and have found that Increasing Poison DC's are few and far between. I have found the Venomous Strike feat that lets you decrease your sneak attack damage by 1d6 to increase the Dc of poison by 2. Now here is the question.
Do Ambush feats stack with themselves? (-2d6=+4 DC. -3d6=+6 ...ect.)

[Crake]

I am building a poisoned based character and have found that Increasing Poison DC's are few and far between. I have found the Venomous Strike feat that lets you decrease your sneak attack damage by 1d6 to increase the Dc of poison by 2. Now here is the question.
Do Ambush feats stack with themselves? (-2d6=+4 DC. -3d6=+6 ...ect.)

Nothing in dnd stacks with itself unless it explicitly says so.

[Temotei]

You can use other Ambush feats to lower saves, though.

[SangoProduction]

Frankly, with the lackluster usefulness of Ambush feats, I'd allow it, as long as it wasn't being used for Black Lotus or Drow Sleep. But it doesn't stack by default.

[CactusAir]

IF you can get Path of War materiel approved for your game, there's several nifty ways to make poison DCs more threatening in there.

but honestly, while ambush feats are a cool idea the implementation has been lackluster at best.

[ShurikVch]

Note: Deep Poisoning feat - in the Dragon #322 - allow to exchange 1d6 SA damage to +1 DC of poison's save - up to +5 (for 5d6 SA)