crassius is actually correct what I meant . but yes the 2 intakes from carb to jug are different. I got the one in my kit which was welded steel and a round hole. which wasn't the same size as the rectangular hole on the cylinder ( when I matched the 2 the motor got a lot more power
as well I noticed that the cnc shorty billet which is port matched at the motor connection is not as big inside diameter as the welded steel. that's actually why I choose to use the steel one and just Dremel it and port match it myself. lol I guess when they make this stuff they are not as concerned with performance as we are trying to build them.
Saying 32mm and 40mm are the same at the intake is too broad a stroke, and as you said the billets, well some but not all are also smaller. Since I run a 16/16 carb I, like you chose a 40mm steel intake and took the dremel to it. I really liked the cast intake but thtat 14.5mm intake made no since to me, and hogging it out leaves it pretty thin walled for cast.
honestly I haven't seen a lot of the different motors and equipment I just have a 50cc and a 50cc for parts and a 66cc I just finished and a 66cc I helped a friend with. so I am a noob. I just watch a lot of you tube and try the stuff I learn