What /6 is Best For Forced Induction 170, 198, or 225?

Speaking from what i see on V8’s, a /6 isn’t going to act to differently than any other engine that is pressurized. So in a way, your correct on all accounts. A lot depends on how you want to play it and for what purpose.

The cylinder head in a N/A engine will flow only so much air. A larger engine ingest more are quicker than a smaller engine. If the head can only feed a 225 to 5000 rpm, the smaller engine will be able to rev higher because of the volume of air it ingests is equal to the volume of the larger engine at a lower rpm.

All of this kind of goes out the window when your pressurized.

Bore and stroke come into play more so at this point. I think bigger is better on engine and turbo.