I have purchased a Carcam for my 991S Cab and up to know I am pleased with it. It is a Nextbase 402G from Halfords, although you can get them cheaper on the web.
My main concern was the size, a bit bigger than some, but it has fitted nicely behind the rear view mirror. I have hidden the cable between the windscreen and the facia and down the left hand side A frame. Using a small non sharp tool the cable can be tucked in the gap. I have used the power from the left hand side passenger power socket. This socket switches itself off after 30 minutes to conserve power. I purchased a 32GB sd card which gives about 4 hours of HD recording.
One of the reasons I went for this make it was the which magazine winner and also has GPS and the software can be played back on a Mac. Some of other softwares do not support mac.

