Hi, 
I'm looking to build myself a set of headers. im thinking tri y might be a good option packaging trying to keep lengths close to equal. 180° is a struggle crossing over, but would 135° pairing be of any benefit? if im looking correct that would pair the outer 2 and inner 2 runners on both heads. Haven't seen a ton of information on headers and calculators seem to give me some outlying runner recommendations. 73" long 3/4 diameter primaries for peak torque at 4k. i know im not going to optimize, but id like to build as decently correct designs. for some reason im not able to get expected results for y blocks from free online calculators, although work normally when using my big block ford specs.
  thanks
Seth