angelpena - they are the original factory pipes, and were a real style statement in the 70s. I've never looked around for pipes for the 350, but I'm sure there will be others on this forum who will have some ideas - might be a good idea to do a search or start a new post about them.
I'm very flattered that you have chosen to use the pic as your wallpaper - I have too!!
Cheers
peter.