I own a set of Vitour Galaxy's (1968 Dodge Dart GTS 383 4-speed) and a set of Cooper Cobra's (1966 Coronet 383-4 / auto) and IMO the Vitours are stickier. Especially for the money! As said, you have to do a half mile of burn outs to really get into the good stuff lol. Hard work if you can get it. As far as the softener I think anything you can do to make the tread sticky without making it gummy/greasy will work. As said design a bolt in ballast for the spare tire well or something. Many of the no prep cars run a ton of rear ballast from my observations.