P38 Seat Band

I've read a couple of posts here about installing a wide band on the P38 seat to provide better lower back support and added pedal power.
Where might this be obtained or how is it made? I would like to do this for added back support. I just replaced my seat laces and that has helped a ton but I'm always looking for new ideas! I don't have back problems but do experience some minor back pain after very long rides.
Thanks for your help.
Scott

Paul W - are you reading this?

I also remember Paul W of Australia mentioning this. I think he took some webbing material used for lawn chairs and tightly stretched a strip across the lumbar region of his Lightning seat.

Paul, if you are reading this, please give us the details of exactly how you did this, and how it helped support your back.

Safe riding,
Joel