front mount cooler gapping with radiator, any preferred gap?

Soon to be mounting a rather large toyosport welly cooler to my vRS and been trying to reasearch gapping to radiators for best airflow results but the web is full of ďifferent answers. One thing I will do is try keep as much of the cars standard plastic shroud to the rad as possible so air cant escape out the sides but wondered what you guys recommend or have done to your cars? Im feeling a half inch gap to stop air turbulence between the 2 and I may change my thermostat to a slightly cooler one if needbe