This may be a dumb question to those who understand this better than I. If the power "spooling" of a smaller turbo is quicker and the larger turbo longer. Wouldn't it make sense to have a bi-turbo that uses two different size turbos?
At lower revs the smaller of the two would deliver the quick response needed off the line and the larger on to keep the power going longer at the top end?
I drive a Bentley Continental V12 Twin Turbo and the turbos kicked in back to back (not at the same time) I am wondering of this technology is even possible with two different size turbos.