I used to run a small coke bottle on 80psi, no problems...Even ran 1 on 100psi once...not at an event though, incase someone found out But it worked well and Ive tested a 2littre coke bottle to the bursting point...sort of. I got it up to about 200psi. Scary...The problem is not usually the bottle itself, but the thread on the end or inside the caps stripping.

But Id always suggest a blowtorch bottle as an upgrade from a coke bottle!

Regards
Dave moulds
Team Turbine