Questions about Windblocker/Windscreen

[bigwatts]

My recently purchased 1997 boxster does not have the wind deflector that sits between the two roll hoops. Is this something that is worthwhile getting? I already have the screens between the hoops. Will the blocker make a big diffrence??

Also, is there any way of telling if the wind screen was ever installed in the car. From some reading I have done in seems like you must get clips and mounts if it has never been installed before. Is this correct?

Also, where is the best place to get the windblocker /windscreen. Best price?? Any suggestions would be greatly appreciated.