Hi Chris, the size of the box itself excluding the plugs on each end is: 110x47x167 (I may be a couple of mill out due to my contortions to get there). There are plugs on each end of the box and including them the overall length is 240.
My unit is mounted unseen behind the glove box, roughly underneath the wiper motor. So from the engine bay all you see are a couple of small bolt heads holding it in place.
The cable for PC etc access "in case" is looped out of the way within the footwell.
Mike.