In advanced measuring blocks, always select RPM, select boost specified, actual and N75 DC%, plus anything else that you want to log. Don't forget to hit the 'turbo' button at the top to increase sample speed.
Start logging before you go WOT so you dont miss anything, can always not graph the useless data. Won't need to repeat it 4 times though, once is ok, twice is plenty. There is a useful marker feature you can use, hit the spacebar while you are logging and it adds a marker in the CSV file to easily find the data you're looking for