Lunati Voodoo 383

To what rpm does your car pull to before you notice a lag in power? I am thinking i need to change the springs out in mine, seems to drop off to early for the cam. I dont even know what springs are in the engine, was even curious the day i bought the car last year since it has 906 heads on it.
Only had it to the track once so far and i was shifting at 6,200 and it felt like it was still pulling. I am running the stock springs that came with the Edelbrocks. The specs are close to what Lunati recommends. They told me i would be fine using those springs.