both of my dusters are getting a 20:1 a 24:1 is to soggy and a 16:1 is to tight and the 20:1 is just right . I drove a car last summer with 20:1 and could not believe the difference . weather P.S.T. will deliver or not is unknown but there are other companys that supply them . I would like to buy from a site supporter if possible .
