the gsx1400 is redlined at 9,000 rpm; however in practice there is little point in taking it past 7,000 because the bike has strong low and mid-range performance. the fuel injection throttle bodies are also fairly small bore and ultimately limit the breathing (and therefore power) of the engine at high revs, this does again however enhance low-end torque and response. conversions including turbocharging and supercharging can be implemented to get around these breathing limitations and deliver significant increases in power and torque.