Hey guys. I was researching this and there seems to be two camps on this. I have a Gravity Pro which falls under the "18 x 20 low powered" racquet category. I am experimenting with tensions. I use Volkl Cyclone mostly. I have always strung above 52lbs but I have read ppl suggest that under 50 is better for 18 x 20 and especially low powered racquets. However, some ppl also suggest above 55 which seems harsh for a full-poly setup. Thoughts?