LOL just found this post after asking the same question a couple of times..
I agree with Weather1967.... I'll admit I have no knowledge of the Boltek system, (I wish I could afford to get one

), but my Hobby-Boards lightning detector is in my loft, fixed along one the sloping rafters.
The manufacturers say it will pick up strikes over 50 miles away, but I've found that strikes even 100 miles away will show up as an increased count, so being in a loft, earthed to the houshold water pipes, doesn't seem to adversely affect the detection.
As to lightning maps, I believe in the Blitzortung and Strikestar maps rather than individual detector maps.
Daryll.