I've just ordered a Toto Ultramax toilet to replace an older Kohler in my bathroom. I have an installation question dealing with which wax ring to use. Should I use one with a plastic horn or just straight wax? The drain pipe diameter is 4-inches and the Kohler was originally installed using a wax ring with a plastic horn. The drain pipe flange sits slightly above the finished floor so I know that one wax ring will do the job.