If it is for bracket racing where you want consistancy and low maintainance, I personally recommend the standard tension oil rings to help keep the combustion chamber clean of oil. You will lose some HP, but if you run several hundred runs (or seasons) between freshening up you would probably want the std tension. If you are looking for every single HP available, then I have heard of using a fish scale to check the drag and fit the oil ring spacer accordingly. I have personally not done this. If you go to low tension oil rings, it is recommended that you also go to a vacuum pump to help with oil control and this can also help free up additional HP.
There are some good engine builders on here that will have some very good inputs on this and how much HP that I am leaving on the table.
Bill M