I'm upgrading from the 25 row Tru-Cool which just wasn't enough for hard track driving in Texas. I decided to go with the Setrab Series 9, 25 row (310mm wide) instead of the Series 6, 34 row (255mm wide) that most people use. They are both rated the same BTU but I think the wider 25 row fits the opening in the Z better and will get better flow.
GTM is using the Series 9 25 row in their kit but they use -8AN lines while I use bigger -10AN.