My FMIC sits around 10mm from the RAD at one end and 20-25mm at the other... The Airtec rad doesnt sit quite square, i had thought about getting another sucker fan on the back of the rad. But the issue is really the airflow over the rad at motorway speeds... I am even thinking about changing the FMIC to a Charge Cooler!
I have a Turbo Cooler before the rad, cooling the hot water from turbo with a small fan on the back of that aswell!