Sorry if this has already been discussed but I did a quick search and did not find an answer in the posts I read. I went to the Sirius website and discovered that they list two different diaphrams for my 1986 Venture Royale. One is a package of four SD1 diaphrams and the other is single SD10's. Anybody know which is the best one for my bike and what the difference would be. They look different from each other in the pictures. Price is similar.