From what I read ASICBOOST gives you a 30% better hash rate, does this only work on all or certain Bitmain asic miners? And how does one enable this hidden feature in these miners?
"Our ASIC chips, like those of some other manufacturers, have a circuit design that supports ASICBOOST." - Bitmain statement
Bitmain claims that it wasn't used on mainnet. It is currently unknown how to make use of the feature. Likely, you'd need custom firmware and software.
Edit: Here's someone on reddit describing how to activate ASICBOOST: https://www.reddit.com/r/Bitcoin/comments/63yo27/some_circumstantial_evidence_supporting_the_claim/dfy5o65/