Light tension rings can seal very well, even without gas porting.
They have no gas pressure to press outwards and seal them when you let off the gas, however.
So this sounds normal for a high performance street car.
Some engine builders want to use a little oil - it means there is adequate piston/ring oiling. It is tough to get it exactly right, and the builder erred on the 'safe' side.
BTW, we are concentrating on your rings, but how about your valves and guides? A little looseness here, or lack of oil control , would cause the same symptoms.
