Finally did the math for the T3 50 trim;
At 20 psi and assuming a 1psi. pressure drop across the intercooler I got a pressure ratio of 2.41
For corrected mass flow rates I got (assuming 90% efficency);
33.47 lbs/min @ 7000 RPM's
28.68 lbs/min @ 6000 RPM's
23.90 lbs/min @ 5000 RPM's
Plotted on the above map;
If the peak boost of 20psi. hits at 5K, it's in the 70% island.
20 psi. at 6k is just off the 65% island.
20 psi. at 7K (redline) is off the map = inefficent/blowing hot air.
The same points (same 20psi.) do look better back on the TO4E 50 trim (see the map in earier post);
Peak boost by 5K is just inside the surge line in the 72% island (could get away a little earlier with antisurge ports).
20 psi at 6K is in the 76% island.
20 psi at 7K (redline) is in the 78% island. Nice cool boost up top.
Again this is only at 20 psi.