There was a big dip in waiver numbers when the renewal process was changed a few years ago, but its rebounded since then. The attendence numbers at the jet events I've been to such as Fl. Jets, Mid-Atlantic, and Liberty Bell, say that turbines are becoming more popular. As far as the engines themselves, the market may be shrinking a bit because the darn things are so reliable. The hottest market for engines seems to be when a new class comes out (like the 36 lb class recently) and everybody moves up. Then guys like me can get their older 27 lb engines on the used market for really good prices
Bob