"40"??  Do you mean bust size??  Because that's the area of the ribcage not the cup size...   the dials increase the size of the breasts, thus changing the cup size and the unimesh dials (V3, V4, A3 etc.) change the assumedly the cupsize and aren't really realistic compared to the real world measurements...  (A,B,C,D etc)  Bear in mind this is just my opinion based on background in design from the late 80's early 90's....  clothing manufacturing may have changed in the last 15-20 years!!! 

Hope this helped in some way!

G

The GR00VY GH0ULIE!

You are pure, you are snow
We are the useless sluts that they mould
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Culture, alienation, boredom and despair