Let's just be clear about one very important thing... dynos vary... it's very possible for a car to produce 300whp on one dyno and 265whp in the same conditions on a different dyno. If a person has only tuned on a conversative dyno, they're idea about what numbers a setup is capable will be considerably different than someone that has only tuned, or uses data from very generous dynos.
I think it's important to remember the point of this discussion... a K04 makes A LOT more power than a K03. If you tell me a K03 made 280whp on 100oct tune with w/m... on that same dyno, in those same conditions, a well tuned K04 with the same mods, 100oct, and w/m would probably make 330whp... and have WAAAAAAAAY less drop off in power in the later RPM's.
Also, there is a huge downside to running a turbo harder than it's designed to be run... sure, you can get more power, but for how long?
A K04 can make a lot more power than a K03 without self destructing.