Has anyone ever used the vinyl dye to change the color of there seats? I would like to know how it turned out. Also what kind should i use?

I have used it but it depends on what you want to cover.  Going from light to dark is ok but it doesn't work very well going the other way and it still takes a couple of coats.  It works almost like dying leather.

Once changed a set of biege seats to white useing a dozen rattle cans of Plasticote vinal spray , seems no amount of "prep" could get all the "body oil" and suntan lotion and armoral out of the vinyl , alas they routinely peeled and had to be touched up I bitched to Plasticote and they sent me a check for 300 bucks to re-upholster (true story)