When you compare 40 & 46 of the same manufacturer and the same model what everyone has said is true. 46 engines are often the same size and slightly lighter when compared to their 40 siblings.

There are also 50, 53, and 55 two stroke engines that are the same size/weight as their 40 counterparts.

Bill, I'll put a Webra 50 or 55 up against the 40 of your choice.