In real life, C4 burns vigorously when set alight, but will not explode even if it is subjected to an enormous impact (pressure) while burning. (The Mythbusters tested this.) The only thing that will detonate C4 is a blasting cap, in which case SPRK or IGNC (ignition cord) is a good TPT substitution. This should be an option that users can choose to turn on or off. Also, perhaps a new element, DCRD (DetCord) could be created.