More opinions, Don't do anything but this, don't go too far, other opinions I have heard say you can take it all the way out to the silencers, cut/don't cut the nubs off the fat part of the V, if you port the top you have to port inlet side or it is a waste of time.
SERIOUSLY?
This seems like Republicans vs Democrats, everyone has an opinion but no one is backing anything up with facts.
so can SOMEONE give the masses a reality of what and what not to do?
Not what we CAN do or WOULD/WOULDN'T do.
Enough research has been done on these things that SOMEONE can say, provide pics, flow numbers etc... for WHAT to do.
I can do the work but need a template to scribe/mark to cut and polish to match.
Not sure IF I am pissing anyone off or not but it is frustrating to think that NO ONE has numbers as to what is BEST to do or TOO FAR and you screw it up facts!
Yes, plenty of research has been done. I think it's sort of a dead horse at this point. That may be why you aren't getting exactly the info you want.
If you want to know what works with an M90, look at Magnum Powers' MPX. Bear in mind that their port design is intended to work with significantly faster rotation of the blower. Also bear in mind that they cast the blower case from scratch. You can't get the same size or shape inlet port that MP did without lots of welding. So it's not really applicable to you.
To put it in general terms:
You have 3 lobes on each rotor, spaced 120 degrees apart. Focus on one side of the blower and imagine the rotor sweeping down toward the inlet, out to the side, and scooping air up along the outside of the case and exhausting it through the outlet port. In order for the blower to work, the following rotor has to seal the inlet port before the leading rotor opens the outlet port. The inlet and outlet ports can't get too close together or the blower will leak air backwards, and it won't make boost. So the distance that you can widen the outlet port is tied to how far you can widen the inlet port. You can widen one a lot, or both a little.
The amount of extra time that the blower spends with both ports sealed directly affects leakage back to the inlet side. To a point, more sealing is better. The stock setup has ports much more than 120 degrees apart, so it is good in regards to sealing.
However, increased sealing time also means that the inlet and outlet ports of the blower would necessarily be smaller ... because the case is a fixed size, and they can only get so far apart. That reduces the ultimate flow capacity of the blower. Once the blower spins really fast, it becomes hard to fill the chamber between the rotors with air in the short time that the inlet port is open. That means less boost is generated.
If you increase the size of the ports, inadvertently making them closer together (again because of the fixed size of the case), then you reduce the sealing time of the rotors. This hurts low-RPM performance because boost will leak backwards. But it increases high-RPM performance. In order to take advantage of the blower's new strengths, you should increase the overdrive of the blower. That spins it faster and keeps it in its most efficient operating range more of the time.
Since you are talking about porting, not welding, it's safe to assume that the inlet will be the most restrictive part of your blower. You can only widen it a little bit, say 3/32" of an inch, and still maintain a workable sealing flange. You can, however, contour the inside of the case so that the air has a little more time to enter the chamber between the rotors.
However far you take the inlet will dictate how far you can take the outlet. You can move it back to the point where the rotors will still seal both ports, plus a little bit for safety. However, it may not make sense to move the blower outlet back as far as you can, because it may already be big enough to move all the air that the inlet can provide. And moving it beyond that point will yield no gain, reduce sealing time, and wear out your tools.
For an example of what works well with a stock case M90, look at what Magnuson Products did when they turned the 94-95 blower into an S-port. It's really not very radical. I think they had the time to figure out if something else would work better, so I think theirs is a good lead to follow.