Originally Posted by
5DIGITS
The talent in playing this balancing act is the willingness to support trade-offs, for the most part.
If a 1:1 ratio is desired on a single turbo application, expect that it will come at the expense of lag, loss of low end torque, etc..
As the pressure ratio climbs, the inverse will occur.
With this, the larger the turbine side, turbine wheel, exhaust ports and supporting exhaust system - the closer you'll be to 1:1.
In contrast, it can also be accomplished by restricting the induction system, reducing cylinder pressures (via spark, boost, cam timing, etc..).
Therefore, it narrows down to how far anyone is willing to go and what the over-all performance expectation is while realizing its manipulation of one piece of a very large puzzle.