if you have the money for the BG400 then get the Spooky Central
its not even close. The GB4000 is 1995 technology with zero upgrades. Spooky is state of the art, cheaper, many more options and penetrates deeper, and has a large free frequency database to use. They also have a forum you can ask questions in and get answers if you run into problems.
/www.spooky2-mall.com/spooky-central-single-generator-kit.htmlforum
/www.spooky2.com/forums/index.php