You're missing the point.
Dwight wondered why a DOHC engine couldn't rev out very high.
The RPM limit on this engine is set by the stroke, not the valve gear.
On a street engine 4000 feet per minute is usually the max.
Some crotch rockets and 4 stroke MXers can go higher, but that's another story.
I wasn't commenting about why the max power was at a certain rpm.
