Rick, hopefully someone like Lynn Farnsworth will comment.  I  have a IV-P that is not done/not flying.  The input I forwarded came from when I designed and machined new intercooler "end caps" for some new intercoolers I decided to use.  The input I got at that time was…..Machine the boss but don't drill the sonic port hole in the angled end cap because the end caps could be used in the Super Legacy.  I am very "engine" knowledgeable but I am NOT a turbo expert.  Frankly, just the opposite.  It is possible the input I received was aimed at the Reno racers.

Craig Berland

Craig,
Thanks for the info!  Some follow-up questions...

Who set up your engine?  Lancair?  Did you (they) get any "official" input from TCM?  Is there anything different in the waste gate (slope) controller or turbos?

Do you have any special power reduction procedures? (i.e. reducing MP slowly to let Upper Deck Pressure bleed off)

Do you have much experience with it up high (i.e. 25,000 ft)?

Perhaps the banter regarding compressor stalls with the sonic nozzles plugged is OWT (Old Wise Tale).  However, know of several straight IV's

(non-P) that still have sonic nozzles because they were told they needed them???

Rick