13psi cap, change to a 180-195* tstat, install a shroud.

btw what year / model vehicle did the water pump come off of, At some point they changed rotation directions on the pump. If your pump is running backwards all its doing is cavitating and not pushing coolant correctly.

Also with a flex fan, the faster it turns the less is does as the blade flatten out. So i would either put a stock fixed fan or a clutch type fan on it. THere are 2 different fixed fans, a 4 blade and a 5 blade (HD cooling).

Where are you located? if in a hotter climate try less anti-freeze more water, say 60/40 mix (h2o / af)