The 337 is a special case because of the design of the aft fuselage and gear doors, and yes on this airplane there is a significant drag rise when retracting the gear so it is recommended that thegear be left down untill the obstacles are cleared. However in the 337 the retraction drag rise is caused by the gear doors. The original poster on this thread was discussing the Cardinal RG, an airplane which never had main gear doors. Incidentally there is a mod for the 337 which eliminates the main gear doors. A 337 that I used to fly had this mod and in addition to greatly simplifying the retractiion system pretty much eliminated the drop in ROC as the gear retracted.