i believe i have the HKS manifold the Abrasive Flow guy extrude honed and flow benched.
before, it flowed more than the extrude honed standard RB25 manifold.
after, the runners flowed more and the % difference in flow was much narrower.
the goss i heard on Abrasive Flow is he has been busy doing LPG installs and has been flat out, therefore doing something profitable while oil prices were higher (apologies if this info is incorrect).