Mostly people don't do anything in the cylinder head department that's correct or verified...they grind away at nothing and 'make big'..'grunt grunt' and there is nothing to tell them if all 8 or 3 or 5 flow the same or worse or equal to the other. Why you tell backyard bob to just go easy... because you can have one flowing 30 cfm more than the rest or none flowing any better.. it's a crap shoot.