I need a 31.6 road post,would the lighter set up be to get a 27.2 post with a shim or get a post already made to 31.6?

I wouln`t temper with the seat post diameter for a mere 30-40 gramms of weight, the post is a savety relevant part. I don`t believe in less diameter and a shim. Just get a light post, tune, AX lightness, use or the like. Forget the campa Record post though, it`s crap. Had one and it broke right off, how nice that was...