Comparing 4k to 6.5k,,,yea. But i see many engines that come on at 5500. now we are back at only a 1500 RPM difference. A 4,7,10mm Serval is FAR,FAR from "pipey". Blip the throttle at almost any REASONABLE rpm, and BOOM, you are in the power. ,,,Afterall we are talking about engines that IDLE at about 1500 rpm..
Im wondering if what you are trying to explain is an engine with good TQ backup and roll-on power without a pipey delivery? I mean, an engine that comes on good at say 5500 RPM and pulls to 10,500 RPM should suit a shorter track or a longer one. Yea? How wide of a spread of power do ya need?