Puzzlement

[mark.e.woodland at gsk.com]

In reading the various threads on 5K, 10 valve turbo upgrades, it sounds
like the K24 spools up faster, delivers more low end torque, but runs out
of juice before the K26, which, in turn, maxes out before the K27, which is
capable of more high end, locomotive-type power... If I've been getting
this correctly.
If the K24 is the hot ticket for the 20v:
A.  Wouldn't the K26 be an upgrade for the 20v?
B.  What are the limitations  of the K24/ 10v head?
Thanks for your consideration, and input.
Mark Woodland