I don't want to sound like an ass, but it's inevitable. What little I know about the Z and aftermarket parts; "Don't buy AMS" Whether it's because they can't measure a pulley, they stole and did a piss-poor job of replicating MSP manifolds, or they just won't admit to bad work it doesn't matter.
There's no way a $150 set of manifolds is trustworthy when it's supposed to be "the same" as a $700 set. Can't moutn something like AMS without a crazy thorough inspection.
In any case, I'm sorry to hear that you got boned and wasted your time all the same.