i moved mine to 6500 but thats only so when im racing other cars on the freeway i can hold it in 4th longer so when i hit 5th im not coming into it a 4k and bogging down.
i usually shift at 5700. no power past there anyways.
A 2V's horsepower is gonna drop off before that. Around 5,300RPM's. Unless you have aftermarket cams and such. The 4V Mach's peak horsepower is at 6,000RPM.
OK at what RPM you shift from one gear to the next has as much to do with trans. gear spread and the amount of RPM's loss / dropped after the shift as anything. A 3.37 first and a 1.99 second means a 41% drop in RPM after shifting. If I shift at 5750 RPM from 1st to 2nd my engine drops to 3395 RPM. The idea is when you shift from 1st to 2nd you want to have the same or more wheel thrust to accelerate the vehicle. Because the % drop is highest in 1st gear you will need to shift 1st at a higher RPM than the other gears.
A 2V's horsepower is gonna drop off before that. Around 5,300RPM's. Unless you have aftermarket cams and such. The 4V Mach's peak horsepower is at 6,000RPM.
Every car is different, so you can't apply this to every stang out there. Ultimately, you can find the best shift points for your car by looking at a dyno graph.