already been done,with fair results,! fact is Cummins diesel had a factory compound engine back in late 80s, In-line 6
company in Austin tx., with lotsa money, and lotsa smart guys , on a Toyota Supra,2JZ, 6cyl. 3.4L.
they spent a long time just trying to tune it, on a chassis dyno and street runs, getting the big atmo. turb. and the small manifold turbo both with wastegates, to open and close or just regulate the flows, finally made around 1000 Whp. you should try setting up 2 (two) ECUs for computor control of the gates,in your spare time, then trying to get the damn computors to work with each other,, NOPE Alex you aint even close Yet!,, forget the mechanical piping & plumbing,thats the easy part.
but there back up car,a Toyota, with big single made,at a dyno shoot out in Houston, made 1400Whp, 3.4L.
Now the good part, the compund setup had much quicker spool on the street, so for street stuff,YEAH maybe OK,, but for all out drag or top end runs a big single still seems to be the answer.
and i personally would not like the idea of,on a V type motor, a big ,and a small, on seperate sides, one of them is gonna fight the other, or something WE havent even thought of YET!!
course maybe Alex will win the lotto, and show us all, i'll be waiting! haha.