Originally Posted by BellIntercooler

The pressure drop, or flow loss can be determined by measuring both air charge values entering and exiting the intercoolerr. Pressure and flow loss are basically drag encountered in the intercooler core it self. Length and density of the tubes have an effect on the loss. Generally, you'd want to limit your loss to about 1-1.5 psi.
Different setups will have different drop values, based on what turbocharger is being used at what boost level, what size core, ent tanks, inlet/outlet size of end tanks, etc.
Hope that answered your question