Is it a smart choice to upgrade the stock radiator cap to something like 1.2 or even 1.3 psi? Or should you just upgrade the coolant to something that doesn't expand that much? Any suggestions on the pros/cons/needs?

 

Depends. If your engine is basically stock, then there isn't much need to upgrade cooling capabilities, just to make it more reliable. Increasing system pressure from 0.9 bar to 1.2 bar (1 bar = 14.6 psi, I think) will only put more mechanical strain on the weak points of the system, so it's definitely not the first thing to do with your cooling system.

Best thing to do is install an accurate water temp gauge, do something about the stock AST, and maybe swap radiators. Then you'll have an idea whether more cooling is necessary and the system will be able to handle it.

Dave