From what I understand, it takes a really long time for the heated bed to heat up using an MK2a heated bed. I've heard some people suggest that using Polyisocyanurate (PIR) foam (insulation that takes quite a bit of heat to catch on fire) can be used under the headed bed to make it heat up faster.
Now of course there are other methods for doing this too, for instance using a larger power supply, but at this point I'd rather just use the parts that I have without re-soldering many of the components on the RAMPS board.
I was wondering what a proper way to attach this to the bed would be for instance, should the springs go on the bottom or on the top of the bed? Do I need some extra parts? Are there any other considerations for doing this?