Actually it's possible.
Download that sound file and put it on ''LFS DIRECTORY\Data\Sound'' and just replace one of the ''Horn1, Horn2, etc.'' files. Then just hit Shift + H at LFS and search for the one you replaced.
That is real good for first vid.
I loved the quality of recording, altought you could press shift+f even for lap times, some cameras wasnt my taste, but i like the footage you did.
Not bad at all man, keep working on those.