That's a lot of faith in a few 2" fabric straps.

I remember when I put my hybrid on a dynojet at Carlisle, their tech drives it but you can sit in the passanger seat. I got in before he pulled it up on the ramp (it's a portable dyno) and by habit put my seatbelt on. He told me it wasn't nessicary, if we came off the dyno, we're screwed, the seatbelt won't help.