"Zero-gap" rings are extremely hard on cylinder walls, resulting in a "barrel-shaped" wear pattern with the majority of the wear about the middle of the piston travel. Unless you're running alcohol/nitromethane fuel and are concerned about the explosive hazard of a mixture of nitro and hot lubricating oil, I can't see a good reason for the expense and wear problems associated with that type of ring. One of my roundtrack race engine customers insisted on them, and wore the cylinders to the point of ruining the block in one race season, about 800 miles of full-throttle operation on a 5/8 mile round track.
Jerry
