SE Sport 200 for a 40 HP? check the size of the anti cav plate.
40HP is the cut off point for changing between the 200 and 300, and there is a fair bit of size difference.
the SE Sport 300 will fit the largest of outboards, ie, up to 300 HP etc, and I wouldn't want that much foil on a little outboard.
http://www.sesport.com/5_29.asp
http://www.sesport.com/5_32.asp
also, some boats need them, and others don't. some boats get really good performance with them, and others turn into dogs.
all depends on the particular boat and its own particular set up
cheers
Mick