I'd been contemplating this first change for a while, then I think JKJ mentioned actually having done it. Two and a half(**) Hackzall blades later – voila! – greatly improved airflow.
Before, some ridiculous airflow blockage in the original casting. Things that make you go "whyyyyyyy":

After, much better:

Related to that, I wanted improved under table collection. I found a seller on Etsy who makes a range of custom under table dust collection solutions for various bandsaws. This design isn't an enclosed box like some approaches posted here. I asked the seller about that regarding the pictured dust chute, since they make both open and enclosed box styles, and he replied that in his experience the open style functions at least as well. I had a 2+" DIY setup there before made wtih ABS pipe partially enclosing the blade, designed for use with a shop vac. This has a big dust collector backing it, and so performs much, much better overall.

(**): I was admittedly impatient and was abusing some EMT conduit blades as I'd run out of the better metal blades...
Before, some ridiculous airflow blockage in the original casting. Things that make you go "whyyyyyyy":

After, much better:

Related to that, I wanted improved under table collection. I found a seller on Etsy who makes a range of custom under table dust collection solutions for various bandsaws. This design isn't an enclosed box like some approaches posted here. I asked the seller about that regarding the pictured dust chute, since they make both open and enclosed box styles, and he replied that in his experience the open style functions at least as well. I had a 2+" DIY setup there before made wtih ABS pipe partially enclosing the blade, designed for use with a shop vac. This has a big dust collector backing it, and so performs much, much better overall.

(**): I was admittedly impatient and was abusing some EMT conduit blades as I'd run out of the better metal blades...
