To make a good naturally aspirated high revving engine you'd need a lot of internal work (I'm not sure you'd ever achieve over 10k more than once though lol) You'd need everything forged/balanced/lightened etc, and a good new ECU mapped and setup. Much easier just doing a turbo'd lump transfer, probably more drivable too mate... If you want a smaller increase on the rev limiter, any piggyback ecu can deliver this, and probably add a good increase in power too, mated to (say) a Glanza S or Starlet Gi inlet manifold ;) that should see ~100bhp Dave