Has anyone fitted an older Nissan 15HP 2-stroke with the 18HP carb? I'm wondering if it's really a plug-n-play operation on the carb only, or are there other items involved? The basic engine block seems to be the same. Would like to know, if it works, would the 3 added horses be noticeable, not speed-wise but power-wise with the properly matched prop. I'm not in a hurry to get anywhere but may want to carry more gear.