When using a limited number of tracks, especially when recording drums with just one or two mics, i've found the following technique helps to beef it out....
Make a group or FX channel, put the multiband compressor that comes with SX3 on this channel, send a signal from the main mix, mess about with it (I always use 4 or 5 bands) until it sounds good. The send from the mix channel can act as an easy way to adjust the input level/threshold on the multiband. The dry mix at the same time adds punch, the multiband adds beef!