Traction lift bar Q's

Can anyone with lift bars give me some info on using them? Are lift bars something you would want to put on a street car, or just a car that sees the track and little street time? Do lift bars actually help lift the front end of the car up? Would putting these on a stock GT make the front end lift up and plant the rear tires for a better ET? Sorry bout all the questions, just saw these while browsing the internet and wanted to know the advatages! Thanks in advance!