P'raps you should build yourself an rb 20 Richard, imagine how wide your power band would be. (they sound orright too)
That an engine with a 10,500 rpm limit can be setup with a wider power band than an engine with an 8,500 rpm limit isnt really rocket science, That the 30 shifts the power band approx 1000 rpm lower is the whole idea of the excercise. Similar overall power and greater torque levels at lower rpm is what motivates most 30 builds that I know of.
Its the old street v track thing. the odd fang to 10500 rpm on the street has none of the perils of a track engine costantly seeing those numbers.
Whilst I hero worship the berry cars along with near everyone who has seen them in action They sound like arse to me. the whole idea of a screamer pipe leaves me scratching my head as to why anybody would want their car to sound like an xb falcon with blown exhaust gaskets when for the sake of plumbing it back they can have the sweet note of a hot rb.