Keep in mind that the stock tach reads 200-400 or more RPM than the engine is actually turning. They can be made to read high RPM accurately, but they will be that same 200-400 or more RPM inaccurate at low or midrange RPM.
The stock EFI computer has a built in rev limiter that cuts off the fuel injectors in sequence, one cylinder at a time. The stock rev limiter starts to limit at 6250 RPM, but a custom tune can change that. Unless you have a really all out combination of heads, cam and intake, you don't need to rev past 5800. The stock engine runs out of power at anything above 5200, so there is no point in winding it much higher.