Just a new top to fit the AMD holes would do. If you knocked up a block I could use while you borrow my maze for testing that'd be OK by me. I'm not bothered how well it performs as long as it's not terrible!
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I like the idea of sqeezing the end of the Cu pipe cause there's a 'continuety' with it that a slot in polycarb would'nt have, a much smoother transition from round to jet shape, if you know what I mean?...