I am just trying to get something straight here. In this pic from what I can figure, the small turbo runs like a single turbo would, sucking in clean air from the big turbo (which isn't spooling much yet) and exhausting it to the big turbo which still doesn't spool so it just passes right through. Then when you step on it, the little one maxes out and opens the wastegate so it will hopefully stop at whatever psi, then the big one gets spooling and provides the cfm necessary to give higher boost, along with being cool air since it is a big turbo.
What I want to know is that, the smaller turbo is basically the same size as the hx35 as far as I can tell, and so I am wondering how that doesn't become a restriction when you need it to be flowing? Also, low end boost is also the same as with just a single HX35, right? In other words, it's not like I can get 5psi at 1000rpm. Right?