[TimS]

Will a driver mounted in a 2" or thicker baffle be acoustically loaded in an undesirable way because the driver is placed in a deep “tunnel” (e.g. the baffle thickness).

If so, does this mean that I should try and remove the mdf/wood from around the rear of the cut driver hole; i.e. shaping it like a funnel leaving scallops(?) for the driver screws to screw into?

Or is this wrong and there is minimal effects of a driver mounted in a thick baffle? The driver I'm using is a SEAS W18.

Thanks

[*Scotty*]

Mounting the driver in even a 3/4in. thick baffle can create a cavity resonance problem that will color the midrange. Danny Richie recommends doing exactly what you proposed, use a router to remove the unwanted material so that you don't have the driver mounted in a tube.
Scotty

[JLM]

Much more important is to provide a reflector of some sort behind the driver, so that the backwave doesn't bounce straight back and through the acoustical semi-transparent cone material that result in smearing of the sound.  (Fostex sells a metal reflector, but recommend something non-resonant.) 

Note that most manufacturers add some sort of lining to try absorbing this, but anything you can add in this extremely high spl environment will help.  (Just think about how much louder sound gets at shorter distances - by a factor of distance squared - plus the small volume, both compared to your room.)  Note also that slanted cabinets have this feature built-in.