using rb25 afms is a cheap way out and not really that effective..
32 gtr running a single gt3582r maxed out the afm voltage at 20psi boost, that means they read 100% air flow either tho the turbo was still sucking in more. you cant put a HP or KW rating on them as such because you can keep tuning the ecu at 100% afm reading it just becomes a very basic tune.
if you use z32 afm's then they will accurately read past 20psi.
personaly I would use a MAP sensored ecu instead even if you run twin turbos