Okay before this becomes completely an argument concerning assumptions and how to predict fan rotational speed vs. airflow and all the assorted good stuff involved, lemme say thanks to everyone. Right now I'm in the middle of doing some hacking/prying/bending/cutting to switch it over to 2x120mm fans on the rad as he has a couple 120mm fans laying around. We're going to take a good look at how that affects things and depending on that, he's going to decide wether or not to start saving up for blocks/pumps for a 3/8" or 1/2" system. If he does that, I'm prolly going to point him in the direction of something like
this or like 2xMCR120s. The transmission cooler matches dimensions of the rad in his exxos much better, and judging from what I've seen of them they would give closer to heatercore performance, but with the thickness being less than half of a normal core (and also a lower FPI count) it should perform better with an axial fan than a core.