I put lowering springs on my car about 6 months ago and wanna go lower...?

i intend on buying a full coilover set to lower my car 4 inches. but i have heard that if i heat up my lowering springs with a little propane torch it will lower it by weight of the car, is this true? if so could i do it and keep them on for a couple weeks before i put my coilovers on without worring about any major problem?