: I agree, 9oz is overkill. As an experienced builder, I recommend that you cut a strip of 6 oz and use it on the bias so that it sits well. This way there will be little chance of seeing the tape through. Cloth tape that is manufactured often has waxes and other material impregnated into it. It usually also has a seam on one edge that is hard to hide unless you pile on layers of resin and then sand down. Best result will be with strip you cut.
Good Luck