BIG Turbo build planned - turbo guys!

And to add to the above.....the rotational inertia of the torque conveter and trannie parts is far higher than any inertia contributed by the rods. So, IMO, the rod inertia is even more down in the noise at the above mentioned RPM ranges. The Al rods could take some load off the crank but again, the RPM's are relatively low; I think your thinking is sound.

Interesting that the RPM stays low in the above examples; that says to me that there IS a flow restriction in addition to the turbo somewhere in the system. I say this because turbo rally cars have been running 35 mm restrictors worldwide for the last 10 years or so, and the RPM's typically flatten out in the 5000-6000 range with the restrictors. Of course, the big boys have figured out how to get around that with different turbos and tuning and fuel mixes. Those 2 to 2.5L 4 cylinder engines put out more usable torque and HP now than without the restictors 10 years ago; they are in the range of 400+ peak HP with a 35 mm diameter restrictor right in front of the turbo...so that shoudl give you some idea how much you can work around any head porting restrictions.