[walker]

Seemed to me the pressure inside could get high 200# or so, but in retrospect I don't think the tubes in the radiator could tolerate that kind of pressure. The biggest enemy is the heat, if you use fuel line the heat will eat it up in short order. So if you use rubber, make sure it is rated for the heat (hydraulic hose). I would recommend bending your own. It is not difficult and is kind of fun. When you need help on the bending, figuring out how to measure your bends, re post. There is an excellent article around here somewhere, or I/other members can point you in the right direction.