Been using this system for fun at the house and training tool at the track. It has been my favorite tool/gadget all year since March. I don't think I'd leave for the track without it.

As far as picking up indoors it is very sensitive and will pickup reflections. I've been messing with placement and using an open cardboard box to place the receiver inside facing the open end has cut down a lot. Also set the minimum lap time in the app helps.