unless you flow test it you can't know.
the jun knock offs for the rb25's we've flow tested at the machine shop next door to our shop and they're ok, but i still chose the GReddy. the GReddy flowed better, fit better, and was easier bolt in with more room left over. plus it's a "real" mod instead of a "i got the cheap shit, and i HOPE it's better than stock cause it still wasn't cheap"
if i had another sr20 an intake manifold would probably be one of the last things i got after the gigantor billy bad ass turbo, rocker arm stoppers, stand alone, injectors, maf/map ^_^, z32 tranny.
i'd get an electric water pump before i got an intake manifold for the sr20.... and they do make em
on rb motors it's a different story. the intake manifold design hinders front mount intercooler piping/spool time. plus being right over the valve cover it heat soaks like a summabich. but for an sr....there's not that issue. so i don't see the point.
Dave =]