FYI, for any of you following my un-pressurized turbo ramblings, here is a picture of a flying Lancair IV I spied at SNF with the upper cowl off. 

 

Note, the sonic nozzles on the back of the intercoolers are plugged (yellow circle in photo).  This is ill-advised with the standard TSIO-550 A/R=.5 turbos.

 

However, it appeared to have larger A/R turbo's, but I could not easily see them due to the lower cowl being on.  Based on a short conversation, I understand it was an IO-550 that was converted/upgraded to a TSIO.

 

I'm chasing more info on it.