I used to detune all my guitars to C-tuning, (full 2steps) and used to use a pack of
ernie ball power slinky's (.11's) with the high e replaced with a .12.
They wer a bit floppy in that tuning (which was really cool for insane string bends
*, so i reckon if you use that on a jem for drop C and put a heavier string on the lowE that that should work out OK.
3 springs is fine, or whatever number you are using now. just adjust the trem thingy in the cavity to get the bridge back into position.
For drop D tuning take your normal E-tuning strings and replace the lowE with one from a pack of your gauge+1's. (same for the drop C, get 11's and a low-E from a pack of 12's), should work.
Mess about with the gauges though, as sometimes a string isn't particularly suites so you might want a thinner or thicker one, but playing with a gauge for a while should tell you enough to know what's best...
Hope this helps...
