Million dollar question.With the angle,the air going into #1 is going to have a short straight run..Not good for "things being equal"department.THe stacks would help,but i can't say if they are the answer.I'm going to be talking to some "in the know" folks soon.I'll put it past them and see what they say.If i were you,i'd start asking some posers to some people that build manifolds for a living.Better to ask questions now.
To be sure of things,you'd want to put the manifold on a flow bench.And i know that's not what you wanted to hear. :(