Replying to Line Anthems mounted back 3cm

Hey, I just bought some line Anthems and I'm having them mounted on the 29th. I ski mostly all mountain and a little bit of dry fluffy powder(Alaska's so dry) and i like to dabble in the park every once and a while. Right now I'm going to mount them -3cm, but i just wanted to see what people thought of that. I know a symmetrical ski should be center mounted but i want a little more stability, speed and float, i can sacrifice a little park performance.