Yet you cant compare these engines with street engines they have
serious internals and money thrown at them.
Many engines can rev high but not be reliable.

The lil A15 can rev to 10000rpm in drag setups in Japan so not bad
for an old pushy engine. If you setup an a15 with a ball bearing
t25rs it will kill a super dooper NA 20v and weigh in the same,
cost less to setup and easier to maintain.
Its just doing it right that few are prepared to do.