This isn't something I can teach you overnight. You need a decent background in physics, including thermal and flow dynamics. You need to research how and why a roots supercharger works.
You can't alter the diagonal lines of the triangular outlet without adversely affecting efficiency. The charge needs to be released at the right moment or point in time. This really isn't something you should attempt until you learn these things for yourself. This is something you should have done for you by someone that does.
Knowing what edges and surfaces to smooth and polish, and knowing WHY is what it'* all about. If I sat down to put it all on paper, I'd have a book by the time I was done. I've personally taken 4 years of research, study, and trial and error to get to the point I'm at now.
Including lots and lots of cad work and analysis:
Not to mention phone conversations over the last couple years with both Eaton and Magnusson Engineers. Yup. Usually dealing with a crappy vendor and getting advice on what should and should not be changed and why. I've bought books and researched for hours before picking up tools. You should do that too.
In other words, until you understand WHY and HOW to do it, don't. Superchargers don't come cheap. I'm not trying to discourage you. I'm trying to discourage you from creating scrap.
Put it off until next season if you need to, but UNDERSTAND it. Get INSIDE that roots blower, and BE THE AIR. It sounds corny, but that'* what it'* all about. Besides, the outlet is the LEAST of your concerns in porting and polishing one of these.