I guess the question most often asked is, "If you had known how long it would take (9 years from idea to STC) and how much (somewhere in the neighborhood of $200,000) would you have still done it?" The answer, of course, is yes. My biggest problem is that I don't know how to promote the Jaguar Cowling or how to market it. I think is sells itself.   Figure about a 5 to 8 knot TAS increase and up to 30 degrees lower CHTs.  (There are 18 Jaguar Cowlings out there.)