Carbuerator Heat Revisited

[hooterg]

When I apply carb heat to my 152 the engine speed drops by 200 rpm - about twice the drop as in the real airplane.  I've looked for a setting in the air and cfg files to adjust the rpm drop but can't find it.  Does anyone know if this is adjustable and, if so, where the adjustment is?  I'm running FS2K2.