Lower temp thermostat-where from?

[cri_ag]

so when you say frothing up you mean cavitation?, your suggesting the solution would be under-driving the water pump? the radiator was not previously ducted in but it is now.

[oldcorollas]

yah, it is a possibility...
paying attention to airflow into and our of the engine bay (and dam area) can make a big difference, but if the pump is trying to move froth, it gets a bit hard..

you'd wan t to be sure it was cavitating before underdriving tho, or try a more efficient impeller shape than pretty much most stock/aftermarket pumps...