Turbo placement for T4 in bug

[Sandeep]

I have plotted my data points on different compressor maps (2000, 3000,4000, 5000 and 6000 rpm) and I have a question.

How do you know when the turbo is starting to boost ? Some points result in a compressor speed of about 70K rpm and some result in over 110K rpm.

Do you want the plotted line to end up in the 'island' mostly, meaning the 6000 rpm data point, or is it ok to have the 6000 rpm data point be off the island ?

I haven't found a site on the web yet that can explain it, and am not confident enough to call a turbo shop and talk 'Turbo' with them

thanks

Sandeep