Rick Writes:

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For anyone who might not have caught/understood this…

I believe, the Mirage .50 A/R is a larger turbo/compressor housing (as expected).  A/R = Area/Radius of the output scroll.  Similar output connector area, larger scroll/housing radius. <snip>

Rick>>>>

Compressor housings for a given model of turbocharger are designed to be interchangeable and therefore have nearly the same R (Scroll Radius) so describing a turbocharger as "bigger" can be misleading. What is important to keep clear is that a higher A/R ratio (0.60) will cause the turbocharger to run slower and produce less boost (pressure ratio) than a lower A/R (0.50) which will cause the turbocharger to run faster and produce more boost. If you don't believe me then read page 19 of Hugh MacInnes' book "Turbochargers".

Regards
Brent Regan