I am just putting together a Blackhorse Extra ARTF and have a choice of 2 engines. Manufacturer recommended engine size is 61 2 stroke or 90 4 stroke. I have a ASP 91 2 stroke and a ASP 91 4 stroke sitting on my shelf looking for a new home. Which should I go with? I have never run the 91 4 stroke but would assume that for overall power the 91 2 stroke would be the better option? Comments and opinions please