Our cooling systems will work fine in stock form for a stock truck. start lifting or adding bumpers and you effect the capability of the cooling system.
I run a stock system with the exception of a mac's aluminum tank (fancy open system swap). No other mods. Clutch fan with stock aux. electric fan for the a.c. No issues. If your having cooling problems it's most likely a sign of underlying, bigger issues.
If I could obtain a good plastic expansion tank I would have been satisfied with the closed system. The mac's tank seemed to be the simplest and most bulletproof solution. So far so good.