I should know more next week when I receive my shipment. I am hoping for a couple of prototypes to start testing. Mark Bullard was instrumental in helping us finish the 91 project and was equally involved in helping us with initial numbers and specs for the 67. If everything goes well, I am hoping to start taking orders by mid summer. There has been tremendous interest in this project, especially from the scale and hydro guys. I am hopful this engine will also pick up more boater interest in running the 60 mono class again. The dual cooling we believe is imperative in installations where limited air cooling is present, such as monos and scale. The hyros have been using the cooling cap only on the 91, and I would think the 67 will be the same. Thanks for the feedback guys. I will keep everyone updated.