Cutting springs or heating them, is not a desireable way to lower your truck. Cutting a coil dimishes the coiling characteristics and eliminates the taper-effect of the top and bottom portion of the coil, where it nests in the pockets of the control arms.
Correct springs or not, it is not recommended to cut coils, however, many do it. Lowering springs are rather economical, so purchasing a new set with the desired drop, is a better route. Not to mention, the original coils have gone through a million spring cycles and may offer a less-than optimum ride.
