Cut is best

Seriously heat? think about the physics of that!

The springs are made of metal.. When you heat metal it goes thru physical change to a more malleable state (depending on temp of heat). That's why the springs "lower".. The metal material is expanding..

When metal is heated it expands and since the mass hasn't changed, then the density is changing.. The density of the metal becomes less..

When you heat springs you are changing the properties of the metal.. IT also becomes more brittle.. = BAD!