Does the Honda 99 si have to be so high on rpm when is 5th gear cause i buy one last week but notice that are like in 5 thousand and am only going 80?

The Honda S2000, not the Honda 99 Si, is known for its high-revving engine. The S2000's engine redlines at 9000 RPM, and it produces its peak power at 8300 RPM. This means that the engine needs to be revved high in order to produce its full power.

As for why the S2000 is in 5th gear at 80 MPH, this is likely due to the car's gearing. The S2000 has a relatively short final drive ratio, which means that the engine has to spin faster in order to achieve a given speed. This can result in the engine being in a higher gear than expected at a given speed.

If you are concerned about the engine RPM being too high, you can try shifting into a higher gear. However, this may result in the engine lugging, which can damage the engine. It is best to consult with a Honda technician to determine the best shifting points for your car.